+
+
+ {/* Mute Button */}
+ {(() => {
+ const muteButton = isMuted
+ ? spriteImagesRef.current.get("mute")
+ : spriteImagesRef.current.get("unmute");
+ if (muteButton) {
+ return (
+
+ );
+ }
+ return null;
+ })()}
+
+ {/* HUD Background */}
+ {gameState === "playing" && (
+
+ )}
+
+ {/* HUD */}
+ {gameState === "playing" && (
+
+
{gameTime}
+
Score: {score}
+
+ Alien Benevolence:
+ 0
+ ? styles.alien
+ : `${styles.alien} ${styles.alienLost}`
+ }
+ >
+ 👽
+
+ 1
+ ? styles.alien
+ : `${styles.alien} ${styles.alienLost}`
+ }
+ >
+ 👽
+
+ 2
+ ? styles.alien
+ : `${styles.alien} ${styles.alienLost}`
+ }
+ >
+ 👽
+
+
+
+ )}
+
+ {/* TEMPORARY Debug Button - Hidden */}
+ {/* {gameState === "playing" && (
+
+ )} */}
+
+ {/* Question Overlay */}
+ {gameState === "playing" &&
+ currentObstacle &&
+ (() => {
+ // Find the live obstacle position from the obstacles array
+ const liveObstacle = obstacles.find(
+ (obs) => obs.id === currentObstacle.id,
+ );
+ const obstacleX = liveObstacle?.x ?? currentObstacle.x;
+ const remainingDistance = obstacleX - COLLISION_ZONE_X;
+ const totalDistance = 700 - COLLISION_ZONE_X;
+ const progressPercent = Math.max(
+ 0,
+ Math.min(
+ 100,
+ (remainingDistance / totalDistance) * 100,
+ ),
+ );
+ const secondsLeft = Math.max(
+ 0,
+ remainingDistance / (SCROLL_SPEED * 60),
+ );
+
+ return (
+
+ {/* Timer Progress Bar */}
+
+
+ totalDistance * 0.66
+ ? "#4CAF50"
+ : remainingDistance >
+ totalDistance * 0.33
+ ? "#FFC107"
+ : "#F44336",
+ }}
+ />
+
+ {secondsLeft.toFixed(1)}s left
+
+
+
+
+
+ {answerFeedback.show && (
+
+ {answerFeedback.message}
+
+ )}
+
+ );
+ })()}
+
+ {/* Benevolence Message */}
+ {benevolenceMessage && (
+
BENEVOLENCE
+ )}
+
+ {/* Car Bonus Scene */}
+ {gameState === "carBonus" && (
+
+ )}
+
+ {/* Start Screen */}
+ {gameState === "start" && (
+
+ {!imagesLoaded &&
Loading sprites...
}
+ {imagesLoaded &&
+ (() => {
+ const titleImage =
+ spriteImagesRef.current.get("title");
+ const startButton =
+ spriteImagesRef.current.get("start");
+
+ if (titleImage && startButton) {
+ return (
+ <>
+
+
+
+ );
+ }
+ return
Loading...
;
+ })()}
+
+ )}
+
+ {/* Story Screen */}
+ {gameState === "story" && (
+
+ {(() => {
+ const storyImg = spriteImagesRef.current.get(
+ `story${storyPage}`,
+ );
+ const nextButton =
+ spriteImagesRef.current.get("next");
+ const startButton =
+ spriteImagesRef.current.get("start");
+ const buttonToUse =
+ storyPage < 7 ? nextButton : startButton;
+
+ if (storyImg && buttonToUse) {
+ return (
+ <>
+
+
+
+ );
+ }
+ return
Loading story...
;
+ })()}
+
+ )}
+
+ {/* Game Over Screen */}
+ {gameState === "gameover" && (
+
+ {(() => {
+ const loseImage =
+ spriteImagesRef.current.get("lose");
+ const startButton =
+ spriteImagesRef.current.get("start");
+ if (loseImage && startButton) {
+ return (
+ <>
+
+
+
+ );
+ }
+ return
Loading game over screen...
;
+ })()}
+
+ )}
+
+ {/* Victory Screen */}
+ {gameState === "victory" && (
+
+ {(() => {
+ const victoryImage =
+ spriteImagesRef.current.get("victory");
+ const startButton =
+ spriteImagesRef.current.get("start");
+ if (victoryImage && startButton) {
+ return (
+ <>
+
+
+
+ );
+ }
+ return
Loading victory screen...
;
+ })()}
+
+ )}
+
+
+ );
+};
+
+const meta: Meta = {
+ title: "Games/Crash Course",
+ component: MathBlasterGame,
+ parameters: {
+ docs: {
+ description: {
+ component:
+ "An endless runner game where players answer math questions to jump over obstacles. " +
+ "Features Perseus widget integration for questions, with support for addition, subtraction, " +
+ "multiplication, and division using numeric-input, expression, and radio widgets.",
+ },
+ },
+ },
+};
+
+export default meta;
+
+type Story = StoryObj
;
+
+export const Default: Story = {};
diff --git a/packages/perseus/src/__docs__/math-blaster-utils.ts b/packages/perseus/src/__docs__/math-blaster-utils.ts
new file mode 100644
index 00000000000..33e0152725c
--- /dev/null
+++ b/packages/perseus/src/__docs__/math-blaster-utils.ts
@@ -0,0 +1,255 @@
+import {getDefaultAnswerArea} from "@khanacademy/perseus-core";
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Question types for the math blaster game
+ */
+export type QuestionType =
+ | "addition"
+ | "subtraction"
+ | "multiplication"
+ | "division";
+
+/**
+ * Generate a random integer between min and max (inclusive)
+ */
+function randomInt(min: number, max: number): number {
+ return Math.floor(Math.random() * (max - min + 1)) + min;
+}
+
+/**
+ * Generate a Perseus item for addition questions
+ */
+function generateAdditionQuestion(): PerseusItem {
+ const a = randomInt(1, 50);
+ const b = randomInt(1, 50);
+ const answer = a + b;
+
+ return {
+ question: {
+ content: `What is $${a} + ${b}$?\n\n[[☃ numeric-input 1]]`,
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: answer,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a Perseus item for subtraction questions
+ */
+function generateSubtractionQuestion(): PerseusItem {
+ const a = randomInt(10, 50);
+ const b = randomInt(1, a); // Ensure positive result
+ const answer = a - b;
+
+ return {
+ question: {
+ content: `What is $${a} - ${b}$?\n\n[[☃ numeric-input 1]]`,
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: answer,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a Perseus item for multiplication questions
+ */
+function generateMultiplicationQuestion(): PerseusItem {
+ const a = randomInt(2, 12);
+ const b = randomInt(2, 12);
+ const answer = a * b;
+
+ return {
+ question: {
+ content: `What is $${a} \\times ${b}$?\n\n[[☃ numeric-input 1]]`,
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: answer,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a Perseus item for division questions
+ */
+function generateDivisionQuestion(): PerseusItem {
+ const divisor = randomInt(2, 12);
+ const quotient = randomInt(2, 12);
+ const dividend = divisor * quotient; // Ensure exact division
+
+ // Generate wrong answers
+ const wrongAnswers = [quotient + 1, quotient - 1, quotient + 2].filter(
+ (val) => val > 0,
+ );
+
+ // Shuffle all answers
+ const allAnswers = [quotient, ...wrongAnswers.slice(0, 3)];
+ const shuffled = allAnswers.sort(() => Math.random() - 0.5);
+
+ const choices = shuffled.map((val, index) => ({
+ id: `choice-${index}-${Date.now()}-${Math.random()}`,
+ content: String(val),
+ correct: val === quotient,
+ }));
+
+ return {
+ question: {
+ content: `What is $${dividend} \\div ${divisor}$?\n\n[[☃ radio 1]]`,
+ images: {},
+ widgets: {
+ "radio 1": {
+ type: "radio",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ choices,
+ randomize: false,
+ multipleSelect: false,
+ hasNoneOfTheAbove: false,
+ deselectEnabled: false,
+ },
+ version: {major: 1, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a random math question
+ */
+export function generateQuestion(): PerseusItem {
+ const types: QuestionType[] = [
+ "addition",
+ "subtraction",
+ "multiplication",
+ "division",
+ ];
+ const randomType = types[randomInt(0, types.length - 1)];
+
+ switch (randomType) {
+ case "addition":
+ return generateAdditionQuestion();
+ case "subtraction":
+ return generateSubtractionQuestion();
+ case "multiplication":
+ return generateMultiplicationQuestion();
+ case "division":
+ return generateDivisionQuestion();
+ }
+}
+
+/**
+ * Obstacle data structure
+ */
+export type Obstacle = {
+ id: string;
+ x: number;
+ y: number;
+ width: number;
+ height: number;
+ question: PerseusItem;
+ answered: boolean;
+ correct: boolean;
+ jumped?: boolean; // Track if we've already triggered jump for this obstacle
+ racing?: boolean; // Track if car is racing away after being jumped
+ racingStartTime?: number; // When the car started racing
+};
+
+/**
+ * Create a new obstacle
+ */
+export function createObstacle(startX: number): Obstacle {
+ return {
+ id: `obstacle-${Date.now()}-${Math.random()}`,
+ x: startX,
+ y: 0, // Ground level
+ width: 154, // Car sprite at 0.6 scale (256 * 0.6)
+ height: 154, // Car sprite at 0.6 scale (256 * 0.6)
+ question: generateQuestion(),
+ answered: false,
+ correct: false,
+ };
+}
diff --git a/packages/perseus/src/__docs__/oldimages/car2.png b/packages/perseus/src/__docs__/oldimages/car2.png
new file mode 100644
index 00000000000..11632e72cad
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diff --git a/packages/perseus/src/__docs__/oldimages/run1.png b/packages/perseus/src/__docs__/oldimages/run1.png
new file mode 100644
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diff --git a/packages/perseus/src/__docs__/oldimages/run2.png b/packages/perseus/src/__docs__/oldimages/run2.png
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diff --git a/packages/perseus/src/__docs__/oldimages/run3.png b/packages/perseus/src/__docs__/oldimages/run3.png
new file mode 100644
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diff --git a/packages/perseus/src/__docs__/oldimages/sky.png b/packages/perseus/src/__docs__/oldimages/sky.png
new file mode 100644
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diff --git a/packages/perseus/src/games/crash-course/README.md b/packages/perseus/src/games/crash-course/README.md
new file mode 100644
index 00000000000..efad8a66d92
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/README.md
@@ -0,0 +1,119 @@
+# Crash Course - Educational Endless Runner
+
+**Status**: 🚧 Under active refactoring (Phase 1 in progress)
+
+Educational endless runner game where players answer math questions while avoiding obstacles.
+
+## Architecture
+
+This game uses a **custom game engine** pattern:
+
+```
+CrashCourseEngine (Pure TypeScript)
+├── 60fps game loop (requestAnimationFrame)
+├── Physics & collision detection
+├── Sprite animation (multi-entity)
+├── Canvas rendering
+└── Perseus question integration
+
+React UI (Thin wrapper)
+├── Game canvas element
+├── UI overlays (start, story, HUD)
+├── Perseus question widget
+└── Event handling (buttons, mute)
+```
+
+## Directory Structure
+
+```
+crash-course/
+├── assets/ # Game assets
+│ ├── sprites/ # Character, alien, car sprites
+│ ├── backgrounds/ # Sky, city layers, lamps
+│ ├── ui/ # Buttons, title, victory/lose screens
+│ ├── audio/ # Music and sound effects
+│ └── story/ # Story page images
+├── engine/ # Game engine (Phase 2)
+│ ├── crash-course-engine.ts # Main engine class
+│ ├── types.ts # Type definitions
+│ ├── systems/ # Reusable systems
+│ └── utils/ # Helper functions
+├── components/ # React UI components (Phase 3)
+├── __tests__/ # Unit tests
+├── __testdata__/ # Test fixtures
+├── __test-utils__/ # Test helpers
+└── plans/ # Refactoring documentation
+```
+
+## Current Status
+
+### ✅ Phase 0: Testing Foundation (Complete)
+- Baseline tests written
+- Performance metrics captured
+- Behavior documented
+
+### 🚧 Phase 1: Setup & Architecture (In Progress)
+- [x] Directory structure created
+- [x] Assets organized
+- [x] Engine API designed
+- [x] Perseus integration interface
+- [ ] Implementation in Phase 2
+
+### 📋 Phase 2: Build Engine (Next)
+- Build CrashCourseEngine class
+- Implement sprite animation system
+- Build game systems (Render, Audio, Assets)
+- Move game logic from React
+
+### 📋 Phase 3: UI Components (Planned)
+- Extract React UI components
+- Wire up engine callbacks
+- Integrate Perseus widget
+
+### 📋 Phase 4: Documentation (Planned)
+- Write comprehensive docs
+- Add code comments
+- Performance verification
+
+## Key Design Decisions
+
+1. **Custom Game Engine**: Avoids React + requestAnimationFrame complexity
+2. **Pure TypeScript**: Game logic independent of React
+3. **60fps Game Loop**: Decoupled from React rendering
+4. **Multi-Entity Sprites**: Built from start to avoid future refactoring
+5. **Perseus Integration**: Standard interface for all educational games
+
+## Documentation
+
+See `plans/` directory for complete refactoring plan:
+- [CRASH_COURSE_CONCEPT.md](./plans/CRASH_COURSE_CONCEPT.md) - Architecture vision
+- [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./plans/CRASH_COURSE_IMPLEMENTATION_PLAN.md) - 5-phase plan
+- [ORIGINAL_BEHAVIOR.md](./plans/ORIGINAL_BEHAVIOR.md) - Current game behavior
+- [PERFORMANCE_BASELINE.md](./plans/PERFORMANCE_BASELINE.md) - Performance metrics
+
+## Running the Game
+
+Currently, the original game still exists at:
+`packages/perseus/src/__docs__/math-blaster-game.stories.tsx`
+
+After refactoring (Phase 3), the new version will be at:
+`packages/perseus/src/games/crash-course/crash-course.stories.tsx`
+
+## Testing
+
+```bash
+# Run tests
+pnpm test packages/perseus/src/games/crash-course
+
+# Run specific test file
+pnpm test crash-course-utils.test.ts
+```
+
+## Contributing
+
+This refactoring follows a 5-phase plan. Please see the phase documents in `plans/` before making changes.
+
+---
+
+**Original**: Math Blaster Game (rapid prototype)
+**Refactored**: Crash Course (production-ready, maintainable)
diff --git a/packages/perseus/src/games/crash-course/__test-utils__/test-utils.ts b/packages/perseus/src/games/crash-course/__test-utils__/test-utils.ts
new file mode 100644
index 00000000000..006e68f44a1
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/__test-utils__/test-utils.ts
@@ -0,0 +1,201 @@
+/**
+ * Test utilities for Crash Course game testing
+ */
+
+/**
+ * Mock canvas element with 2D context
+ */
+export function mockCanvas(): HTMLCanvasElement {
+ const canvas = document.createElement("canvas");
+ canvas.width = 800;
+ canvas.height = 600;
+
+ const ctx = {
+ // Drawing methods
+ clearRect: jest.fn(),
+ fillRect: jest.fn(),
+ strokeRect: jest.fn(),
+ beginPath: jest.fn(),
+ closePath: jest.fn(),
+ moveTo: jest.fn(),
+ lineTo: jest.fn(),
+ arc: jest.fn(),
+ fill: jest.fn(),
+ stroke: jest.fn(),
+
+ // Image drawing
+ drawImage: jest.fn(),
+
+ // Text
+ fillText: jest.fn(),
+ strokeText: jest.fn(),
+ measureText: jest.fn(() => ({width: 100})),
+
+ // Transforms
+ save: jest.fn(),
+ restore: jest.fn(),
+ translate: jest.fn(),
+ rotate: jest.fn(),
+ scale: jest.fn(),
+ transform: jest.fn(),
+ setTransform: jest.fn(),
+
+ // Properties
+ fillStyle: "#000000",
+ strokeStyle: "#000000",
+ lineWidth: 1,
+ lineCap: "butt",
+ lineJoin: "miter",
+ globalAlpha: 1,
+ globalCompositeOperation: "source-over",
+ font: "10px sans-serif",
+ textAlign: "start",
+ textBaseline: "alphabetic",
+
+ // Gradients and patterns
+ createLinearGradient: jest.fn(),
+ createRadialGradient: jest.fn(),
+ createPattern: jest.fn(),
+
+ // Pixel manipulation
+ getImageData: jest.fn(),
+ putImageData: jest.fn(),
+ createImageData: jest.fn(),
+ };
+
+ // Mock getContext to return our mock context
+ canvas.getContext = jest.fn((contextType: string) => {
+ if (contextType === "2d") {
+ return ctx as any;
+ }
+ return null;
+ });
+
+ return canvas;
+}
+
+/**
+ * Mock audio element
+ */
+export function mockAudio(): HTMLAudioElement {
+ const audio = {
+ // Methods
+ play: jest.fn().mockResolvedValue(undefined),
+ pause: jest.fn(),
+ load: jest.fn(),
+
+ // Properties
+ currentTime: 0,
+ duration: 0,
+ volume: 1,
+ muted: false,
+ paused: true,
+ ended: false,
+ loop: false,
+ src: "",
+
+ // Events
+ addEventListener: jest.fn(),
+ removeEventListener: jest.fn(),
+ dispatchEvent: jest.fn(),
+ };
+
+ return audio as any;
+}
+
+/**
+ * Mock Image element
+ */
+export function mockImage(src?: string): HTMLImageElement {
+ const image = {
+ src: src || "",
+ width: 128,
+ height: 128,
+ complete: true,
+ addEventListener: jest.fn((event: string, callback: Function) => {
+ // Immediately trigger onload for testing
+ if (event === "load") {
+ setTimeout(() => callback(), 0);
+ }
+ }),
+ removeEventListener: jest.fn(),
+ };
+
+ return image as any;
+}
+
+/**
+ * Advance game time by specified milliseconds
+ */
+export function advanceGameTime(ms: number): void {
+ jest.advanceTimersByTime(ms);
+}
+
+/**
+ * Setup fake timers for testing
+ */
+export function setupFakeTimers(): void {
+ jest.useFakeTimers();
+}
+
+/**
+ * Restore real timers after testing
+ */
+export function restoreTimers(): void {
+ jest.useRealTimers();
+}
+
+/**
+ * Mock requestAnimationFrame for testing
+ */
+export function mockRequestAnimationFrame(): {
+ mock: jest.Mock;
+ trigger: () => void;
+} {
+ let callback: FrameRequestCallback | null = null;
+ let frameId = 1;
+
+ const mock = jest.fn((cb: FrameRequestCallback) => {
+ callback = cb;
+ return frameId++;
+ });
+
+ const trigger = () => {
+ if (callback) {
+ callback(performance.now());
+ }
+ };
+
+ global.requestAnimationFrame = mock as any;
+
+ return {mock, trigger};
+}
+
+/**
+ * Mock cancelAnimationFrame for testing
+ */
+export function mockCancelAnimationFrame(): jest.Mock {
+ const mock = jest.fn();
+ global.cancelAnimationFrame = mock as any;
+ return mock;
+}
+
+/**
+ * Wait for next tick (useful for async operations)
+ */
+export function waitForNextTick(): Promise {
+ return new Promise((resolve) => setImmediate(resolve));
+}
+
+/**
+ * Create a mock collision scenario
+ */
+export function createMockCollision(
+ obstacleX: number,
+ obstacleWidth: number = 154,
+ characterX: number = 100,
+ characterWidth: number = 128,
+): boolean {
+ const collisionZoneX = characterX + characterWidth + 20;
+ return obstacleX < collisionZoneX && obstacleX + obstacleWidth > characterX;
+}
diff --git a/packages/perseus/src/games/crash-course/__testdata__/questions.testdata.ts b/packages/perseus/src/games/crash-course/__testdata__/questions.testdata.ts
new file mode 100644
index 00000000000..bf66f6dd610
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/__testdata__/questions.testdata.ts
@@ -0,0 +1,177 @@
+/**
+ * Test data for Perseus questions used in Crash Course game
+ */
+import {getDefaultAnswerArea} from "@khanacademy/perseus-core";
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Example addition question: 12 + 8 = 20
+ */
+export const additionQuestion: PerseusItem = {
+ question: {
+ content: "What is $12 + 8$?\n\n[[☃ numeric-input 1]]",
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: 20,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+};
+
+/**
+ * Example subtraction question: 25 - 10 = 15
+ */
+export const subtractionQuestion: PerseusItem = {
+ question: {
+ content: "What is $25 - 10$?\n\n[[☃ numeric-input 1]]",
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: 15,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+};
+
+/**
+ * Example multiplication question: 6 × 7 = 42
+ */
+export const multiplicationQuestion: PerseusItem = {
+ question: {
+ content: "What is $6 \\times 7$?\n\n[[☃ numeric-input 1]]",
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: 42,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+};
+
+/**
+ * Example division question: 24 ÷ 6 = 4
+ */
+export const divisionQuestion: PerseusItem = {
+ question: {
+ content: "What is $24 \\div 6$?\n\n[[☃ radio 1]]",
+ images: {},
+ widgets: {
+ "radio 1": {
+ type: "radio",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ choices: [
+ {
+ id: "choice-1",
+ content: "3",
+ correct: false,
+ },
+ {
+ id: "choice-2",
+ content: "4",
+ correct: true,
+ },
+ {
+ id: "choice-3",
+ content: "5",
+ correct: false,
+ },
+ {
+ id: "choice-4",
+ content: "6",
+ correct: false,
+ },
+ ],
+ randomize: false,
+ multipleSelect: false,
+ hasNoneOfTheAbove: false,
+ deselectEnabled: false,
+ },
+ version: {major: 1, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+};
+
+/**
+ * All question examples for easy iteration
+ */
+export const allQuestions = [
+ additionQuestion,
+ subtractionQuestion,
+ multiplicationQuestion,
+ divisionQuestion,
+];
diff --git a/packages/perseus/src/games/crash-course/__tests__/crash-course-utils.test.ts b/packages/perseus/src/games/crash-course/__tests__/crash-course-utils.test.ts
new file mode 100644
index 00000000000..f772b00922b
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/__tests__/crash-course-utils.test.ts
@@ -0,0 +1,157 @@
+/**
+ * Baseline tests for Crash Course utility functions
+ *
+ * These tests capture the current behavior before refactoring.
+ */
+import {createObstacle, generateQuestion} from "../../../__docs__/math-blaster-utils";
+
+describe("Crash Course Utils (Baseline)", () => {
+ describe("generateQuestion", () => {
+ it("generates a valid Perseus item structure", () => {
+ //Arrange, Act
+ const question = generateQuestion();
+
+ //Assert
+ expect(question).toHaveProperty("question");
+ expect(question).toHaveProperty("answerArea");
+ expect(question).toHaveProperty("itemDataVersion");
+ expect(question).toHaveProperty("hints");
+ expect(question.question).toHaveProperty("content");
+ expect(question.question).toHaveProperty("images");
+ expect(question.question).toHaveProperty("widgets");
+ });
+ });
+
+ describe("createObstacle", () => {
+ it("creates obstacle at specified x position", () => {
+ //Arrange, Act
+ const obstacle = createObstacle(800);
+
+ //Assert
+ expect(obstacle.x).toBe(800);
+ });
+
+ it("creates obstacle with correct dimensions", () => {
+ //Arrange, Act
+ const obstacle = createObstacle(500);
+
+ //Assert
+ expect(obstacle.width).toBe(154); // Car sprite at 0.6 scale
+ expect(obstacle.height).toBe(154);
+ expect(obstacle.y).toBe(0); // Ground level
+ });
+
+ it("creates obstacle with a question", () => {
+ //Arrange, Act
+ const obstacle = createObstacle(600);
+
+ //Assert
+ expect(obstacle.question).toBeDefined();
+ expect(obstacle.question).toHaveProperty("question");
+ expect(obstacle.question.question).toHaveProperty("content");
+ });
+
+ it("creates obstacle with unique id", () => {
+ //Arrange, Act
+ const obstacle1 = createObstacle(100);
+ const obstacle2 = createObstacle(200);
+
+ //Assert
+ expect(obstacle1.id).not.toBe(obstacle2.id);
+ expect(obstacle1.id).toMatch(/^obstacle-/);
+ expect(obstacle2.id).toMatch(/^obstacle-/);
+ });
+
+ it("creates obstacle with default state", () => {
+ //Arrange, Act
+ const obstacle = createObstacle(400);
+
+ //Assert
+ expect(obstacle.answered).toBe(false);
+ expect(obstacle.correct).toBe(false);
+ expect(obstacle.jumped).toBeUndefined();
+ expect(obstacle.racing).toBeUndefined();
+ });
+
+ it("creates multiple obstacles with different questions", () => {
+ //Arrange, Act
+ const obstacles = Array.from({length: 10}, (_, i) =>
+ createObstacle(i * 100),
+ );
+
+ //Assert
+ // Should have different questions (very unlikely to be all the same)
+ const uniqueQuestions = new Set(
+ obstacles.map((o) => o.question.question.content),
+ );
+ expect(uniqueQuestions.size).toBeGreaterThan(1);
+ });
+ });
+
+ describe("Collision Detection (Logic)", () => {
+ it("detects collision when obstacle in collision zone", () => {
+ //Arrange
+ const obstacleX = 100;
+ const obstacleWidth = 154;
+ const characterX = 100;
+ const characterWidth = 128;
+ const collisionZoneX = characterX + characterWidth + 20;
+
+ //Act
+ const isInZone =
+ obstacleX < collisionZoneX &&
+ obstacleX + obstacleWidth > characterX;
+
+ //Assert
+ expect(isInZone).toBe(true);
+ });
+
+ it("no collision when obstacle far to the right", () => {
+ //Arrange
+ const obstacleX = 800;
+ const obstacleWidth = 154;
+ const characterX = 100;
+ const characterWidth = 128;
+ const collisionZoneX = characterX + characterWidth + 20;
+
+ //Act
+ const isInZone =
+ obstacleX < collisionZoneX &&
+ obstacleX + obstacleWidth > characterX;
+
+ //Assert
+ expect(isInZone).toBe(false);
+ });
+
+ it("no collision when obstacle passed character", () => {
+ //Arrange
+ const obstacleX = -200; // Passed the character
+ const obstacleWidth = 154;
+ const characterX = 100;
+ const characterWidth = 128;
+ const collisionZoneX = characterX + characterWidth + 20;
+
+ //Act
+ const isInZone =
+ obstacleX < collisionZoneX &&
+ obstacleX + obstacleWidth > characterX;
+
+ //Assert
+ expect(isInZone).toBe(false);
+ });
+
+ it("collision zone is ahead of character", () => {
+ //Arrange
+ const characterX = 100;
+ const characterWidth = 128;
+
+ //Act
+ const collisionZoneX = characterX + characterWidth + 20;
+
+ //Assert
+ // Collision zone should be to the right of the character
+ expect(collisionZoneX).toBe(248);
+ expect(collisionZoneX).toBeGreaterThan(characterX + characterWidth);
+ });
+ });
+});
diff --git a/packages/perseus/src/games/crash-course/assets/ASSETS.md b/packages/perseus/src/games/crash-course/assets/ASSETS.md
new file mode 100644
index 00000000000..f475ec70018
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/assets/ASSETS.md
@@ -0,0 +1,171 @@
+# Crash Course Assets
+
+This directory contains all game assets organized by type.
+
+## Directory Structure
+
+```
+assets/
+├── sprites/ # Character, alien, and car sprites
+├── backgrounds/ # Sky, city layers, and environmental elements
+├── ui/ # UI elements (buttons, titles, screens)
+├── audio/ # Music tracks and sound effects
+└── story/ # Story sequence images
+```
+
+## Asset Inventory
+
+### Sprites (`sprites/`)
+
+**Character Animation (128x128px)**:
+- `run1.png` through `run6.png` - Running animation (6 frames)
+- `impact.png` - Impact/collision effect
+
+**Aliens (300x300px)**:
+- `alien1.png`, `alien2.png`, `alien3.png` - Alien animation frames
+- `beam.png` - Abduction beam effect
+
+**Obstacles**:
+- `car1.png`, `car2.png` - Car obstacles (256x256px)
+
+### Backgrounds (`backgrounds/`)
+
+**Sky & City Layers (parallax scrolling)**:
+- `sky.png` - Static sky background (800x600px)
+- `city-far.png` - Distant city layer (slowest parallax)
+- `city-semi-far.png` - Semi-distant city layer
+- `city-semi-close.png` - Semi-close city layer
+- `city-close.png` - Closest city layer (fastest parallax)
+
+**Environmental**:
+- `streetlamp.png` - Street lamp sprite
+- `lamplight.png` - Lamp glow effect
+
+### UI (`ui/`)
+
+**Screens**:
+- `title.png` - Game title logo
+- `start.png` - Start button
+- `victory.png` - Victory screen
+- `lose.png` - Game over screen
+
+**Buttons**:
+- `next.png` - Next button (story pages)
+- `mute.png` - Mute audio icon
+- `unmute.png` - Unmute audio icon
+
+**Special**:
+- `bonus1.png`, `bonus2.png` - Car bonus animation frames
+- `skid.png` - Skid mark effect
+
+### Story (`story/`)
+
+**Story Sequence (7 pages)**:
+- `story1.png` through `story7.png` - Narrative intro sequence
+
+### Audio (`audio/`)
+
+**Music Tracks (OGG format)**:
+- `alexbouncymix2.ogg` - Menu/story music (loops)
+- `Zodik - Tedox.ogg` - Gameplay music (plays once)
+- `Zodik - Neon Owl.ogg` - Extended gameplay music (loops)
+- `Game Over II.ogg` - Game over music
+
+**Sound Effects (WAV format)**:
+- `bonusgame.wav` - Bonus level music
+- `explosion.wav` - Explosion sound
+- `tires_squal_loop.wav` - Tire squeal sound
+
+## Import Examples
+
+### In Engine/Systems (Phase 2)
+
+```typescript
+// Import sprites
+import run1 from "../assets/sprites/run1.png";
+import alien1 from "../assets/sprites/alien1.png";
+
+// Import backgrounds
+import skyImg from "../assets/backgrounds/sky.png";
+import cityFar from "../assets/backgrounds/city-far.png";
+
+// Import UI
+import titleImg from "../assets/ui/title.png";
+import startBtn from "../assets/ui/start.png";
+
+// Import audio
+import menuMusic from "../assets/audio/alexbouncymix2.ogg";
+import gameplayMusic from "../assets/audio/Zodik - Tedox.ogg";
+
+// Import story
+import story1 from "../assets/story/story1.png";
+```
+
+### In React Components (Phase 3)
+
+```typescript
+// UI assets for overlays
+import titleImg from "../../assets/ui/title.png";
+import startBtn from "../../assets/ui/start.png";
+import muteIcon from "../../assets/ui/mute.png";
+```
+
+## Asset Manifest
+
+For the AssetLoader system (Phase 2), assets will be defined in a manifest:
+
+```typescript
+const ASSET_MANIFEST = {
+ images: {
+ // Sprites
+ run1: run1Img,
+ run2: run2Img,
+ // ... etc
+
+ // Backgrounds
+ sky: skyImg,
+ cityFar: cityFarImg,
+ // ... etc
+ },
+ audio: {
+ menu: menuMusic,
+ gameplay: gameplayMusic,
+ extended: neonOwlMusic,
+ gameover: gameOverMusic,
+ },
+};
+```
+
+## File Formats
+
+- **Images**: PNG (with transparency where needed)
+- **Audio**: OGG Vorbis (web-optimized)
+
+## Size Guidelines
+
+- Character sprites: 128x128px
+- Alien sprites: 300x300px
+- Car sprites: 256x256px
+- Backgrounds: 800x600px (full canvas) or wider for parallax
+- UI elements: Variable (optimized for 800x600 canvas)
+
+## Asset Credits
+
+- Music: Zodik, Alex
+- Art: [To be added]
+
+## Notes for Phase 2
+
+When building the AssetLoader:
+1. Load all images on init()
+2. Create Image elements for each sprite
+3. Create Audio elements for each track
+4. Track loading progress
+5. Resolve promise when all loaded
+6. Provide getImage() and getAudio() accessors
+
+---
+
+**All assets moved from**: `packages/perseus/src/__docs__/`
+**Moved to**: `packages/perseus/src/games/crash-course/assets/`
+**Date**: 2025-01-07 (Phase 1)
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/lose.png b/packages/perseus/src/games/crash-course/assets/ui/lose.png
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/next.png b/packages/perseus/src/games/crash-course/assets/ui/next.png
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/skid.png b/packages/perseus/src/games/crash-course/assets/ui/skid.png
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/start.png b/packages/perseus/src/games/crash-course/assets/ui/start.png
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/title.png b/packages/perseus/src/games/crash-course/assets/ui/title.png
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/unmute.png b/packages/perseus/src/games/crash-course/assets/ui/unmute.png
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diff --git a/packages/perseus/src/games/crash-course/assets/ui/victory.png b/packages/perseus/src/games/crash-course/assets/ui/victory.png
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diff --git a/packages/perseus/src/games/crash-course/engine/animated-sprite.ts b/packages/perseus/src/games/crash-course/engine/animated-sprite.ts
new file mode 100644
index 00000000000..8258b13ebee
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/animated-sprite.ts
@@ -0,0 +1,222 @@
+/**
+ * Animated Sprite
+ *
+ * High-level sprite entity that combines position, size, and animation.
+ * Makes working with sprites easier by handling position + drawing together.
+ */
+import {SpriteAnimator} from "./sprite-animator";
+
+import type {SpriteEffect} from "./types";
+
+/**
+ * A sprite entity with position, size, and animation
+ */
+export class AnimatedSprite {
+ // Position and size
+ public x: number;
+ public y: number;
+ public width: number;
+ public height: number;
+
+ // Rendering
+ public layer: string;
+ public opacity: number = 1;
+ public visible: boolean = true;
+
+ // Animation
+ private animator: SpriteAnimator;
+
+ constructor(
+ animator: SpriteAnimator,
+ x: number = 0,
+ y: number = 0,
+ width: number = 128,
+ height: number = 128,
+ layer: string = "default",
+ ) {
+ this.animator = animator;
+ this.x = x;
+ this.y = y;
+ this.width = width;
+ this.height = height;
+ this.layer = layer;
+ }
+
+ /**
+ * Play an animation
+ */
+ play(name: string, restart: boolean = false): void {
+ this.animator.play(name, restart);
+ }
+
+ /**
+ * Stop the animation
+ */
+ stop(): void {
+ this.animator.stop();
+ }
+
+ /**
+ * Pause the animation
+ */
+ pause(): void {
+ this.animator.pause();
+ }
+
+ /**
+ * Resume the animation
+ */
+ resume(): void {
+ this.animator.resume();
+ }
+
+ /**
+ * Update the animation
+ */
+ update(deltaTime: number): void {
+ this.animator.update(deltaTime);
+ }
+
+ /**
+ * Draw the sprite to a canvas context
+ */
+ draw(ctx: CanvasRenderingContext2D): void {
+ if (!this.visible) return;
+
+ const frame = this.animator.getCurrentFrame();
+ if (!frame) return;
+
+ const effect = this.animator.getEffect();
+
+ ctx.save();
+
+ // Apply opacity
+ ctx.globalAlpha = this.opacity;
+
+ // Apply effects
+ if (effect) {
+ this.applyEffect(ctx, effect);
+ }
+
+ // Draw the sprite
+ ctx.drawImage(frame, this.x, this.y, this.width, this.height);
+
+ ctx.restore();
+ }
+
+ /**
+ * Apply visual effects
+ */
+ private applyEffect(
+ ctx: CanvasRenderingContext2D,
+ effect: SpriteEffect,
+ ): void {
+ if (!effect) return;
+
+ switch (effect.type) {
+ case "shake":
+ this.x += (Math.random() - 0.5) * effect.intensity;
+ this.y += (Math.random() - 0.5) * effect.intensity;
+ break;
+
+ case "tint":
+ ctx.fillStyle = effect.color;
+ ctx.globalCompositeOperation = "multiply";
+ break;
+
+ case "opacity":
+ ctx.globalAlpha *= effect.value;
+ break;
+ }
+ }
+
+ /**
+ * Set a visual effect
+ */
+ setEffect(effect: SpriteEffect): void {
+ this.animator.setEffect(effect);
+ }
+
+ /**
+ * Clear the effect
+ */
+ clearEffect(): void {
+ this.animator.clearEffect();
+ }
+
+ /**
+ * Get bounding box for collision detection
+ */
+ getBoundingBox(): {x: number; y: number; width: number; height: number} {
+ return {
+ x: this.x,
+ y: this.y,
+ width: this.width,
+ height: this.height,
+ };
+ }
+
+ /**
+ * Check if this sprite overlaps with another
+ */
+ overlaps(other: AnimatedSprite): boolean {
+ return (
+ this.x < other.x + other.width &&
+ this.x + this.width > other.x &&
+ this.y < other.y + other.height &&
+ this.y + this.height > other.y
+ );
+ }
+
+ /**
+ * Check if a point is inside this sprite
+ */
+ containsPoint(x: number, y: number): boolean {
+ return (
+ x >= this.x &&
+ x <= this.x + this.width &&
+ y >= this.y &&
+ y <= this.y + this.height
+ );
+ }
+
+ /**
+ * Get the center point of the sprite
+ */
+ getCenter(): {x: number; y: number} {
+ return {
+ x: this.x + this.width / 2,
+ y: this.y + this.height / 2,
+ };
+ }
+
+ /**
+ * Set position
+ */
+ setPosition(x: number, y: number): void {
+ this.x = x;
+ this.y = y;
+ }
+
+ /**
+ * Move by delta
+ */
+ moveBy(dx: number, dy: number): void {
+ this.x += dx;
+ this.y += dy;
+ }
+
+ /**
+ * Get current animation name
+ */
+ getCurrentAnimation(): string | null {
+ return this.animator.getCurrentAnimationName();
+ }
+
+ /**
+ * Check if animating
+ */
+ isAnimating(): boolean {
+ return this.animator.isAnimating();
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/asset-manifest.ts b/packages/perseus/src/games/crash-course/engine/asset-manifest.ts
new file mode 100644
index 00000000000..a0fd689fcd1
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/asset-manifest.ts
@@ -0,0 +1,114 @@
+/**
+ * Asset Manifest
+ *
+ * Defines all game assets (images and audio) that need to be loaded.
+ * Used by AssetLoader to preload and cache assets before game starts.
+ */
+import type {AssetManifest} from "./types";
+
+// Import all sprite assets
+import alien1 from "../assets/sprites/alien1.png";
+import alien2 from "../assets/sprites/alien2.png";
+import alien3 from "../assets/sprites/alien3.png";
+import beam from "../assets/sprites/beam.png";
+import car1 from "../assets/sprites/car1.png";
+import impact from "../assets/sprites/impact.png";
+import run1 from "../assets/sprites/run1.png";
+import run2 from "../assets/sprites/run2.png";
+import run3 from "../assets/sprites/run3.png";
+import run4 from "../assets/sprites/run4.png";
+import run5 from "../assets/sprites/run5.png";
+import run6 from "../assets/sprites/run6.png";
+
+// Import background assets
+import cityClose from "../assets/backgrounds/city-close.png";
+import cityFar from "../assets/backgrounds/city-far.png";
+import citySemiClose from "../assets/backgrounds/city-semi-close.png";
+import citySemiFar from "../assets/backgrounds/city-semi-far.png";
+import lamplight from "../assets/backgrounds/lamplight.png";
+import sky from "../assets/backgrounds/sky.png";
+import streetlamp from "../assets/backgrounds/streetlamp.png";
+
+// Import UI assets
+import lose from "../assets/ui/lose.png";
+import mute from "../assets/ui/mute.png";
+import next from "../assets/ui/next.png";
+import start from "../assets/ui/start.png";
+import title from "../assets/ui/title.png";
+import unmute from "../assets/ui/unmute.png";
+import victory from "../assets/ui/victory.png";
+
+// Import story assets
+import story1 from "../assets/story/story1.png";
+import story2 from "../assets/story/story2.png";
+import story3 from "../assets/story/story3.png";
+import story4 from "../assets/story/story4.png";
+import story5 from "../assets/story/story5.png";
+import story6 from "../assets/story/story6.png";
+import story7 from "../assets/story/story7.png";
+
+// Import audio assets
+import alexBouncyMix from "../assets/audio/alexbouncymix2.ogg";
+import gameOver from "../assets/audio/Game Over II.ogg";
+import neonOwl from "../assets/audio/Zodik - Neon Owl.ogg";
+import tedox from "../assets/audio/Zodik - Tedox.ogg";
+
+/**
+ * Game asset manifest
+ * Maps asset keys to their file paths
+ */
+export const ASSET_MANIFEST: AssetManifest = {
+ images: {
+ // Character sprites
+ "run1": run1,
+ "run2": run2,
+ "run3": run3,
+ "run4": run4,
+ "run5": run5,
+ "run6": run6,
+ "impact": impact,
+
+ // Alien sprites
+ "alien1": alien1,
+ "alien2": alien2,
+ "alien3": alien3,
+ "beam": beam,
+
+ // Obstacle sprites
+ "car1": car1,
+
+ // Backgrounds
+ "sky": sky,
+ "cityFar": cityFar,
+ "citySemiFar": citySemiFar,
+ "citySemiClose": citySemiClose,
+ "cityClose": cityClose,
+ "streetlamp": streetlamp,
+ "lamplight": lamplight,
+
+ // UI
+ "title": title,
+ "start": start,
+ "next": next,
+ "victory": victory,
+ "lose": lose,
+ "mute": mute,
+ "unmute": unmute,
+
+ // Story
+ "story1": story1,
+ "story2": story2,
+ "story3": story3,
+ "story4": story4,
+ "story5": story5,
+ "story6": story6,
+ "story7": story7,
+ },
+ audio: {
+ // Music tracks
+ "menu": alexBouncyMix,
+ "gameplay": tedox,
+ "extended": neonOwl,
+ "gameover": gameOver,
+ },
+};
diff --git a/packages/perseus/src/games/crash-course/engine/constants.ts b/packages/perseus/src/games/crash-course/engine/constants.ts
new file mode 100644
index 00000000000..68caeae939d
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/constants.ts
@@ -0,0 +1,88 @@
+/**
+ * Game Constants
+ *
+ * Central location for all game configuration values.
+ * Makes it easy to tune gameplay and maintain consistency.
+ */
+
+/**
+ * Canvas dimensions
+ */
+export const CANVAS_WIDTH = 800;
+export const CANVAS_HEIGHT = 600;
+
+/**
+ * Ground and positioning
+ */
+export const GROUND_Y = 450;
+export const CHARACTER_X = 100;
+export const SPRITE_SIZE = 128;
+
+/**
+ * Physics constants
+ */
+export const JUMP_HEIGHT = 140;
+export const JUMP_DURATION = 1000; // milliseconds
+export const SCROLL_SPEED = 2; // pixels per frame
+
+/**
+ * Gameplay timing
+ */
+export const OBSTACLE_SPAWN_INTERVAL = 5000; // milliseconds
+export const COOL_MODE_DURATION = 2000; // milliseconds
+export const GAME_DURATION = 300000; // 5 minutes in milliseconds
+
+/**
+ * Collision detection
+ */
+export const COLLISION_ZONE_X = CHARACTER_X + SPRITE_SIZE + 20;
+export const COLLISION_ZONE_WIDTH = 100;
+export const QUESTION_DISPLAY_DISTANCE = 700; // Show question when obstacle is this close
+
+/**
+ * Parallax scrolling speeds (relative to SCROLL_SPEED)
+ */
+export const PARALLAX_SPEEDS = {
+ cityFar: 0.2,
+ citySemiFar: 0.4,
+ citySemiClose: 0.6,
+ cityClose: 0.8,
+} as const;
+
+/**
+ * Parallax layer Y positions and heights
+ */
+export const PARALLAX_LAYERS = {
+ cityFar: {y: 250, height: 200},
+ citySemiFar: {y: 300, height: 150},
+ citySemiClose: {y: 350, height: 100},
+ cityClose: {y: 380, height: 70},
+} as const;
+
+/**
+ * Streetlamp configuration
+ */
+export const LAMP_SPACING = 500;
+export const LAMP_LIGHT_Y_OFFSET = -300;
+
+/**
+ * Obstacle (car) configuration
+ */
+export const CAR_WIDTH = 154; // 256 * 0.6 scale
+export const CAR_HEIGHT = 154;
+
+/**
+ * Character animation FPS
+ */
+export const CHARACTER_ANIMATION_FPS = 8;
+
+/**
+ * Initial player stats
+ */
+export const STARTING_LIVES = 3;
+export const STARTING_SCORE = 0;
+
+/**
+ * Cool mode effect color
+ */
+export const COOL_MODE_TINT = "#9370DB"; // Medium purple
diff --git a/packages/perseus/src/games/crash-course/engine/crash-course-engine.ts b/packages/perseus/src/games/crash-course/engine/crash-course-engine.ts
new file mode 100644
index 00000000000..d3734dd46e1
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/crash-course-engine.ts
@@ -0,0 +1,814 @@
+/**
+ * Crash Course Game Engine
+ *
+ * Main game engine class that runs the 60fps game loop independently of React.
+ * Handles physics, collision detection, sprite animation, and Perseus question integration.
+ */
+import {AssetLoader} from "./systems/asset-loader";
+import {AudioSystem} from "./systems/audio-system";
+import {RenderSystem} from "./systems/render-system";
+import {PhysicsSystem} from "./systems/physics-system";
+import {SpriteManager} from "./sprite-manager";
+import {ASSET_MANIFEST} from "./asset-manifest";
+import {generateQuestion} from "./question-generator";
+import * as CONSTANTS from "./constants";
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+import type {PerseusGameEngine} from "../../shared/perseus/perseus-game-engine";
+import type {EngineConfig, GameState, GameUIState, Obstacle} from "./types";
+
+/**
+ * Main game engine for Crash Course
+ */
+export class CrashCourseEngine implements PerseusGameEngine {
+ // Canvas
+ private canvas: HTMLCanvasElement;
+ private ctx: CanvasRenderingContext2D;
+
+ // Callbacks
+ private onUIUpdate: (state: GameUIState) => void;
+ private questionChangeCallback: ((question: PerseusItem | null) => void) | null = null;
+
+ // Game loop
+ private animationFrameId: number | null = null;
+ private lastTime: number = 0;
+ private isRunning: boolean = false;
+ private frameCount: number = 0;
+
+ // Game state
+ private gameState: GameState = "start";
+ private previousGameState: GameState = "start";
+ private storyPage: number = 1;
+ private score: number = 0;
+ private lives: number = 3;
+ private gameStartTime: number = 0;
+ private showBenevolence: boolean = false;
+ private isMuted: boolean = false;
+
+ // Perseus integration
+ private currentQuestion: PerseusItem | null = null;
+
+ // Game entities
+ private obstacles: Obstacle[] = [];
+ private lastSpawnTime: number = 0;
+
+ // Rendering state
+ private parallaxOffsets = {
+ cityFar: 0,
+ citySemiFar: 0,
+ citySemiClose: 0,
+ cityClose: 0,
+ };
+ private lampOffset: number = 0;
+
+ // Engine systems
+ private assetLoader: AssetLoader;
+ private audioSystem: AudioSystem;
+ private renderSystem: RenderSystem;
+ private physicsSystem: PhysicsSystem;
+ private spriteManager: SpriteManager;
+
+ // Sprite IDs
+ private characterSpriteId = "character";
+ private alienSpriteId = "alien";
+
+ constructor(config: EngineConfig) {
+ this.canvas = config.canvas;
+ const ctx = this.canvas.getContext("2d");
+ if (!ctx) {
+ throw new Error("Failed to get 2D context from canvas");
+ }
+ this.ctx = ctx;
+ this.onUIUpdate = config.onUIUpdate;
+
+ // Initialize systems
+ this.assetLoader = new AssetLoader();
+ this.audioSystem = new AudioSystem();
+ this.renderSystem = new RenderSystem(this.canvas);
+ this.physicsSystem = new PhysicsSystem(CONSTANTS.GROUND_Y);
+ this.spriteManager = new SpriteManager(this.assetLoader);
+ }
+
+ /**
+ * Initialize the game engine and load all assets
+ */
+ async init(): Promise {
+ // Load all game assets
+ await this.assetLoader.loadAssets(ASSET_MANIFEST);
+
+ // Register audio tracks with the audio system
+ const menuAudio = this.assetLoader.getAudio("menu");
+ const gameplayAudio = this.assetLoader.getAudio("gameplay");
+ const extendedAudio = this.assetLoader.getAudio("extended");
+ const gameoverAudio = this.assetLoader.getAudio("gameover");
+
+ if (menuAudio) this.audioSystem.registerTrack("menu", menuAudio);
+ if (gameplayAudio)
+ this.audioSystem.registerTrack("gameplay", gameplayAudio);
+ if (extendedAudio)
+ this.audioSystem.registerTrack("extended", extendedAudio);
+ if (gameoverAudio)
+ this.audioSystem.registerTrack("gameover", gameoverAudio);
+
+ // Set up audio transitions: when gameplay music ends, start extended
+ if (gameplayAudio && extendedAudio) {
+ this.audioSystem.setupTransition("gameplay", "extended");
+ }
+
+ // Create character sprite with animations
+ await this.createCharacterSprite();
+
+ console.log("Engine initialized - assets loaded");
+ }
+
+ /**
+ * Create character sprite with all animations
+ */
+ private async createCharacterSprite(): Promise {
+ // Create character sprite with all animation frames
+ await this.spriteManager.create(this.characterSpriteId, {
+ frames: ["run1", "run2", "run3", "run4", "run5", "run6", "impact"],
+ animations: {
+ running: {
+ frames: [0, 1, 2, 3, 4, 5], // run1-run6
+ fps: CONSTANTS.CHARACTER_ANIMATION_FPS,
+ loop: true,
+ },
+ coolMode: {
+ frames: [0, 1, 2, 3, 4, 5], // run1-run6 (will add purple tint)
+ fps: CONSTANTS.CHARACTER_ANIMATION_FPS,
+ loop: true,
+ },
+ impact: {
+ frames: [6], // impact frame
+ fps: 1,
+ loop: false,
+ },
+ loss: {
+ frames: [0], // run1 (character being abducted)
+ fps: 1,
+ loop: false,
+ },
+ },
+ position: {
+ x: CONSTANTS.CHARACTER_X,
+ y: CONSTANTS.GROUND_Y,
+ },
+ size: {
+ width: CONSTANTS.SPRITE_SIZE,
+ height: CONSTANTS.SPRITE_SIZE,
+ },
+ layer: "character",
+ });
+
+ // Start with running animation
+ this.spriteManager.play(this.characterSpriteId, "running");
+ }
+
+ /**
+ * Start the game loop
+ */
+ start(): void {
+ this.isRunning = true;
+ this.lastTime = performance.now();
+ this.gameLoop(this.lastTime);
+ }
+
+ /**
+ * Stop the game loop and clean up
+ */
+ stop(): void {
+ this.isRunning = false;
+ if (this.animationFrameId !== null) {
+ cancelAnimationFrame(this.animationFrameId);
+ this.animationFrameId = null;
+ }
+
+ // Clean up systems
+ this.audioSystem.cleanup();
+ this.spriteManager.clear();
+ }
+
+ /**
+ * Pause the game
+ */
+ pause(): void {
+ this.isRunning = false;
+ }
+
+ /**
+ * Resume the game
+ */
+ resume(): void {
+ if (!this.isRunning) {
+ this.isRunning = true;
+ this.lastTime = performance.now();
+ this.gameLoop(this.lastTime);
+ }
+ }
+
+ /**
+ * Main game loop - runs at 60fps
+ */
+ private gameLoop = (currentTime: number): void => {
+ if (!this.isRunning) return;
+
+ const deltaTime = currentTime - this.lastTime;
+ this.lastTime = currentTime;
+
+ // Update game logic
+ this.update(deltaTime);
+
+ // Render to canvas
+ this.render();
+
+ // Notify React of UI state changes (throttled to ~10fps)
+ this.frameCount++;
+ if (this.frameCount % 6 === 0) {
+ this.notifyUIUpdate();
+ }
+
+ // Continue loop
+ this.animationFrameId = requestAnimationFrame(this.gameLoop);
+ };
+
+ /**
+ * Update game logic
+ */
+ private update(deltaTime: number): void {
+ // Only update game logic when playing
+ if (this.gameState !== "playing") {
+ return;
+ }
+
+ // Update physics (jumping, character state)
+ this.physicsSystem.update(deltaTime);
+
+ // Sync character sprite with physics state
+ this.syncCharacterSprite();
+
+ // Update sprite animations
+ this.spriteManager.updateAll(deltaTime);
+
+ // Update parallax scrolling
+ this.parallaxOffsets.cityFar +=
+ CONSTANTS.SCROLL_SPEED * CONSTANTS.PARALLAX_SPEEDS.cityFar;
+ this.parallaxOffsets.citySemiFar +=
+ CONSTANTS.SCROLL_SPEED * CONSTANTS.PARALLAX_SPEEDS.citySemiFar;
+ this.parallaxOffsets.citySemiClose +=
+ CONSTANTS.SCROLL_SPEED * CONSTANTS.PARALLAX_SPEEDS.citySemiClose;
+ this.parallaxOffsets.cityClose +=
+ CONSTANTS.SCROLL_SPEED * CONSTANTS.PARALLAX_SPEEDS.cityClose;
+ this.lampOffset += CONSTANTS.SCROLL_SPEED;
+
+ // Update obstacles (move them left)
+ const currentTime = Date.now();
+
+ this.obstacles = this.obstacles.filter((obs) => {
+ obs.x -= CONSTANTS.SCROLL_SPEED;
+
+ // Check collision if obstacle is in collision zone and not answered
+ if (
+ !obs.answered &&
+ !obs.jumped &&
+ this.physicsSystem.checkCollisionZone(obs)
+ ) {
+ // If character is jumping, mark as jumped
+ if (this.physicsSystem.isJumping()) {
+ obs.jumped = true;
+ obs.racing = true;
+ obs.racingStartTime = currentTime;
+ }
+ // If not jumping and colliding, trigger impact (unless in cool mode)
+ else if (this.physicsSystem.getState() !== "coolMode") {
+ const collision = this.physicsSystem.checkCollision(obs);
+ if (collision) {
+ this.physicsSystem.triggerImpact();
+ // TODO: Handle collision consequences
+ }
+ }
+ }
+
+ // Remove obstacles that are off-screen
+ return obs.x + obs.width > 0;
+ });
+
+ // Spawn new obstacles
+ if (
+ currentTime - this.lastSpawnTime >
+ CONSTANTS.OBSTACLE_SPAWN_INTERVAL
+ ) {
+ this.spawnObstacle();
+ this.lastSpawnTime = currentTime;
+ }
+
+ // Update current question based on closest obstacle
+ this.updateCurrentQuestion();
+
+ // Check victory condition (5 minutes elapsed)
+ if (currentTime - this.gameStartTime >= CONSTANTS.GAME_DURATION) {
+ this.transitionToState("victory");
+ }
+ }
+
+ /**
+ * Render everything to canvas
+ */
+ private render(): void {
+ // Clear canvas
+ this.renderSystem.clear();
+
+ // Only render game visuals during playing state
+ if (this.gameState !== "playing") {
+ return;
+ }
+
+ // Draw sky background (static)
+ const skyImg = this.assetLoader.getImage("sky");
+ if (skyImg) {
+ this.renderSystem.drawImage(
+ skyImg,
+ 0,
+ 0,
+ CONSTANTS.CANVAS_WIDTH,
+ CONSTANTS.CANVAS_HEIGHT,
+ );
+ }
+
+ // Draw parallax city layers
+ const cityFarImg = this.assetLoader.getImage("cityFar");
+ const citySemiFarImg = this.assetLoader.getImage("citySemiFar");
+ const citySemiCloseImg = this.assetLoader.getImage("citySemiClose");
+ const cityCloseImg = this.assetLoader.getImage("cityClose");
+
+ if (cityFarImg) {
+ this.renderSystem.drawParallaxLayer(
+ cityFarImg,
+ this.parallaxOffsets.cityFar,
+ CONSTANTS.PARALLAX_LAYERS.cityFar.y,
+ CONSTANTS.PARALLAX_LAYERS.cityFar.height,
+ );
+ }
+ if (citySemiFarImg) {
+ this.renderSystem.drawParallaxLayer(
+ citySemiFarImg,
+ this.parallaxOffsets.citySemiFar,
+ CONSTANTS.PARALLAX_LAYERS.citySemiFar.y,
+ CONSTANTS.PARALLAX_LAYERS.citySemiFar.height,
+ );
+ }
+ if (citySemiCloseImg) {
+ this.renderSystem.drawParallaxLayer(
+ citySemiCloseImg,
+ this.parallaxOffsets.citySemiClose,
+ CONSTANTS.PARALLAX_LAYERS.citySemiClose.y,
+ CONSTANTS.PARALLAX_LAYERS.citySemiClose.height,
+ );
+ }
+ if (cityCloseImg) {
+ this.renderSystem.drawParallaxLayer(
+ cityCloseImg,
+ this.parallaxOffsets.cityClose,
+ CONSTANTS.PARALLAX_LAYERS.cityClose.y,
+ CONSTANTS.PARALLAX_LAYERS.cityClose.height,
+ );
+ }
+
+ // Draw ground
+ this.renderSystem.drawRect(
+ 0,
+ CONSTANTS.GROUND_Y,
+ CONSTANTS.CANVAS_WIDTH,
+ 150,
+ "#2a2a2a",
+ );
+
+ // Draw streetlamps with lights
+ this.drawStreetlamps();
+
+ // Draw obstacles (cars)
+ this.drawObstacles();
+
+ // Draw character
+ this.drawCharacter();
+ }
+
+ /**
+ * Draw streetlamps with their lights
+ */
+ private drawStreetlamps(): void {
+ const streetlampImg = this.assetLoader.getImage("streetlamp");
+ const lamplightImg = this.assetLoader.getImage("lamplight");
+
+ if (!streetlampImg || !lamplightImg) {
+ return;
+ }
+
+ // Calculate how many lamps we need to cover the screen plus overflow
+ const numLamps =
+ Math.ceil(CONSTANTS.CANVAS_WIDTH / CONSTANTS.LAMP_SPACING) + 2;
+
+ for (let i = 0; i < numLamps; i++) {
+ const baseX = i * CONSTANTS.LAMP_SPACING;
+ const x = baseX - (this.lampOffset % CONSTANTS.LAMP_SPACING);
+
+ // Draw lamplight glow
+ this.renderSystem.drawImage(
+ lamplightImg,
+ x - lamplightImg.width / 2,
+ CONSTANTS.GROUND_Y + CONSTANTS.LAMP_LIGHT_Y_OFFSET,
+ lamplightImg.width,
+ lamplightImg.height,
+ );
+
+ // Draw streetlamp
+ this.renderSystem.drawImage(
+ streetlampImg,
+ x - streetlampImg.width / 2,
+ CONSTANTS.GROUND_Y - streetlampImg.height,
+ streetlampImg.width,
+ streetlampImg.height,
+ );
+ }
+ }
+
+ /**
+ * Draw obstacles (cars)
+ */
+ private drawObstacles(): void {
+ const carImg = this.assetLoader.getImage("car1");
+
+ if (!carImg) {
+ return;
+ }
+
+ for (const obs of this.obstacles) {
+ // Calculate Y position based on ground
+ const carY = CONSTANTS.GROUND_Y - obs.height;
+
+ // Draw car at obstacle position
+ this.renderSystem.drawImage(
+ carImg,
+ obs.x,
+ carY,
+ obs.width,
+ obs.height,
+ );
+ }
+ }
+
+ /**
+ * Sync character sprite with physics state
+ */
+ private syncCharacterSprite(): void {
+ const characterPhysics = this.physicsSystem.getCharacterState();
+ const characterSprite = this.spriteManager.get(this.characterSpriteId);
+
+ if (!characterSprite) {
+ return;
+ }
+
+ // Update position to match physics
+ characterSprite.setPosition(characterPhysics.x, characterPhysics.y);
+
+ // Update animation based on state
+ const currentAnim = characterSprite.getCurrentAnimation();
+ const desiredAnim = this.getCharacterAnimation(characterPhysics.state);
+
+ if (currentAnim !== desiredAnim) {
+ this.spriteManager.play(this.characterSpriteId, desiredAnim);
+
+ // Add purple tint for cool mode
+ if (characterPhysics.state === "coolMode") {
+ characterSprite.setEffect({
+ type: "tint",
+ color: CONSTANTS.COOL_MODE_TINT,
+ });
+ } else {
+ characterSprite.clearEffect();
+ }
+ }
+ }
+
+ /**
+ * Get animation name for character state
+ */
+ private getCharacterAnimation(state: CharacterState): string {
+ switch (state) {
+ case "running":
+ return "running";
+ case "coolMode":
+ return "coolMode";
+ case "impact":
+ return "impact";
+ case "loss":
+ return "loss";
+ default:
+ return "running";
+ }
+ }
+
+ /**
+ * Draw character using sprite system
+ */
+ private drawCharacter(): void {
+ const characterSprite = this.spriteManager.get(this.characterSpriteId);
+
+ if (!characterSprite) {
+ return;
+ }
+
+ // Draw character sprite
+ characterSprite.draw(this.ctx);
+ }
+
+ /**
+ * Notify React of UI state changes
+ */
+ private notifyUIUpdate(): void {
+ this.onUIUpdate(this.getUIState());
+ }
+
+ /**
+ * Spawn a new obstacle with a question
+ */
+ private spawnObstacle(): void {
+ const obstacle: Obstacle = {
+ id: `obstacle-${Date.now()}-${Math.random()}`,
+ x: CONSTANTS.CANVAS_WIDTH,
+ y: 0, // Ground level (will adjust in rendering)
+ width: CONSTANTS.CAR_WIDTH,
+ height: CONSTANTS.CAR_HEIGHT,
+ question: generateQuestion(),
+ answered: false,
+ correct: false,
+ };
+ this.obstacles.push(obstacle);
+ }
+
+ /**
+ * Update current question based on closest obstacle
+ * Question is shown when obstacle is within threshold distance
+ */
+ private updateCurrentQuestion(): void {
+ const closestObstacle = this.obstacles.find(
+ (obs) =>
+ !obs.answered && obs.x < CONSTANTS.QUESTION_DISPLAY_DISTANCE,
+ );
+
+ // If we have a new obstacle to show, update current question
+ if (
+ closestObstacle &&
+ closestObstacle.question !== this.currentQuestion
+ ) {
+ this.currentQuestion = closestObstacle.question;
+ this.notifyQuestionChange();
+ } else if (!closestObstacle && this.currentQuestion !== null) {
+ // No more close obstacles, clear question
+ this.currentQuestion = null;
+ this.notifyQuestionChange();
+ }
+ }
+
+ /**
+ * Get current UI state for React
+ */
+ private getUIState(): GameUIState {
+ return {
+ gameState: this.gameState,
+ storyPage: this.storyPage,
+ score: this.score,
+ lives: this.lives,
+ gameTime: this.formatGameTime(),
+ currentQuestion: this.currentQuestion,
+ showBenevolence: this.showBenevolence,
+ isMuted: this.isMuted,
+ };
+ }
+
+ /**
+ * Format game time for display
+ */
+ private formatGameTime(): string {
+ if (this.gameState !== "playing" && this.gameState !== "victory") {
+ return "11:55:00";
+ }
+
+ const elapsed = Date.now() - this.gameStartTime;
+ const totalSeconds = Math.floor(elapsed / 1000);
+ const minutes = 55 + Math.floor(totalSeconds / 60);
+ const seconds = totalSeconds % 60;
+
+ // Game lasts 5 minutes (until midnight)
+ if (minutes >= 60) {
+ return "12:00:00";
+ }
+
+ return `11:${minutes.toString().padStart(2, "0")}:${seconds.toString().padStart(2, "0")}`;
+ }
+
+ /**
+ * Handle user actions from React (button clicks, etc.)
+ */
+ handleAction(action: string, data?: any): void {
+ switch (action) {
+ case "startGame":
+ this.transitionToState("story");
+ break;
+ case "nextStoryPage":
+ if (this.storyPage < 7) {
+ this.storyPage++;
+ } else {
+ this.transitionToState("playing");
+ }
+ break;
+ case "jump":
+ // Allow jumping during gameplay
+ if (this.gameState === "playing") {
+ this.physicsSystem.jump();
+ }
+ break;
+ case "toggleMute":
+ this.isMuted = !this.isMuted;
+ this.audioSystem.setMuted(this.isMuted);
+ break;
+ case "restart":
+ this.transitionToState("start");
+ break;
+ default:
+ console.warn(`Unknown action: ${action}`);
+ }
+ }
+
+ /**
+ * Transition to a new game state with proper entry/exit logic
+ */
+ private transitionToState(newState: GameState): void {
+ if (this.gameState === newState) {
+ return;
+ }
+
+ // Exit current state
+ this.exitState(this.gameState);
+
+ // Update state
+ this.previousGameState = this.gameState;
+ this.gameState = newState;
+
+ // Enter new state
+ this.enterState(newState);
+ }
+
+ /**
+ * Handle state exit logic
+ */
+ private exitState(state: GameState): void {
+ switch (state) {
+ case "playing":
+ // Clean up gameplay state
+ this.obstacles = [];
+ this.currentQuestion = null;
+ break;
+ }
+ }
+
+ /**
+ * Handle state entry logic
+ */
+ private enterState(state: GameState): void {
+ switch (state) {
+ case "start":
+ // Reset to menu
+ this.storyPage = 1;
+ this.score = CONSTANTS.STARTING_SCORE;
+ this.lives = CONSTANTS.STARTING_LIVES;
+ this.gameStartTime = 0;
+ this.lastSpawnTime = 0;
+ this.obstacles = [];
+ this.currentQuestion = null;
+ this.showBenevolence = false;
+ this.physicsSystem.reset();
+ // Play menu music
+ this.audioSystem.play("menu");
+ break;
+
+ case "story":
+ // Start story sequence
+ this.storyPage = 1;
+ this.physicsSystem.reset();
+ // Start gameplay music when story begins
+ this.audioSystem.play("gameplay");
+ break;
+
+ case "playing":
+ // Start gameplay
+ this.gameStartTime = Date.now();
+ this.lastSpawnTime = Date.now();
+ this.score = CONSTANTS.STARTING_SCORE;
+ this.lives = CONSTANTS.STARTING_LIVES;
+ this.obstacles = [];
+ this.currentQuestion = null;
+ this.physicsSystem.resetToRunning();
+ // Reset parallax offsets
+ this.parallaxOffsets = {
+ cityFar: 0,
+ citySemiFar: 0,
+ citySemiClose: 0,
+ cityClose: 0,
+ };
+ this.lampOffset = 0;
+ // Reset character sprite animation
+ this.spriteManager.play(this.characterSpriteId, "running");
+ const characterSprite = this.spriteManager.get(
+ this.characterSpriteId,
+ );
+ if (characterSprite) {
+ characterSprite.clearEffect();
+ }
+ // Gameplay music should already be playing from story state
+ break;
+
+ case "victory":
+ // Victory state - music continues playing
+ break;
+
+ case "gameover":
+ // Game over - play game over music
+ this.audioSystem.play("gameover");
+ break;
+
+ case "carBonus":
+ // Bonus scene (not implemented yet)
+ break;
+ }
+ }
+
+ // Perseus Integration Interface
+
+ /**
+ * Get the currently active Perseus question
+ */
+ getCurrentQuestion(): PerseusItem | null {
+ return this.currentQuestion;
+ }
+
+ /**
+ * Submit an answer to the current question
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void {
+ if (!this.currentQuestion) {
+ return;
+ }
+
+ // Find the obstacle with this question
+ const obstacle = this.obstacles.find(
+ (obs) => obs.question === this.currentQuestion && !obs.answered,
+ );
+
+ if (!obstacle) {
+ return;
+ }
+
+ // Mark obstacle as answered
+ obstacle.answered = true;
+ obstacle.correct = correct;
+
+ if (correct) {
+ // Correct answer: increase score, trigger cool mode
+ this.score += earnedPoints;
+ this.physicsSystem.triggerCoolMode();
+ } else {
+ // Incorrect answer: lose a life, trigger alien abduction
+ this.lives = Math.max(0, this.lives - 1);
+ this.physicsSystem.triggerLoss();
+ // TODO: Task 13 - Trigger alien abduction animation
+
+ // Check for game over
+ if (this.lives === 0) {
+ this.transitionToState("gameover");
+ }
+ }
+
+ // Clear current question
+ this.currentQuestion = null;
+ this.notifyQuestionChange();
+ }
+
+ /**
+ * Register a callback for when the question changes
+ */
+ onQuestionChange(
+ callback: (question: PerseusItem | null) => void,
+ ): void {
+ this.questionChangeCallback = callback;
+ }
+
+ /**
+ * Notify React that the question has changed
+ */
+ private notifyQuestionChange(): void {
+ if (this.questionChangeCallback) {
+ this.questionChangeCallback(this.currentQuestion);
+ }
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/index.ts b/packages/perseus/src/games/crash-course/engine/index.ts
new file mode 100644
index 00000000000..e4898a96ca9
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/index.ts
@@ -0,0 +1,13 @@
+/**
+ * Crash Course Game Engine
+ *
+ * Exports the main engine class and types for external use.
+ */
+export {CrashCourseEngine} from "./crash-course-engine";
+export type {
+ GameState,
+ GameUIState,
+ EngineConfig,
+ Obstacle,
+ CharacterState,
+} from "./types";
diff --git a/packages/perseus/src/games/crash-course/engine/question-generator.ts b/packages/perseus/src/games/crash-course/engine/question-generator.ts
new file mode 100644
index 00000000000..159aa82d7d5
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/question-generator.ts
@@ -0,0 +1,228 @@
+/**
+ * Question Generator
+ *
+ * Generates random Perseus math questions for the game.
+ * Questions include addition, subtraction, multiplication, and division.
+ */
+import {getDefaultAnswerArea} from "@khanacademy/perseus-core";
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Question types for the math blaster game
+ */
+export type QuestionType =
+ | "addition"
+ | "subtraction"
+ | "multiplication"
+ | "division";
+
+/**
+ * Generate a random integer between min and max (inclusive)
+ */
+function randomInt(min: number, max: number): number {
+ return Math.floor(Math.random() * (max - min + 1)) + min;
+}
+
+/**
+ * Generate a Perseus item for addition questions
+ */
+function generateAdditionQuestion(): PerseusItem {
+ const a = randomInt(1, 50);
+ const b = randomInt(1, 50);
+ const answer = a + b;
+
+ return {
+ question: {
+ content: `What is $${a} + ${b}$?\n\n[[☃ numeric-input 1]]`,
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: answer,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a Perseus item for subtraction questions
+ */
+function generateSubtractionQuestion(): PerseusItem {
+ const a = randomInt(10, 50);
+ const b = randomInt(1, a); // Ensure positive result
+ const answer = a - b;
+
+ return {
+ question: {
+ content: `What is $${a} - ${b}$?\n\n[[☃ numeric-input 1]]`,
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: answer,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a Perseus item for multiplication questions
+ */
+function generateMultiplicationQuestion(): PerseusItem {
+ const a = randomInt(2, 12);
+ const b = randomInt(2, 12);
+ const answer = a * b;
+
+ return {
+ question: {
+ content: `What is $${a} \\times ${b}$?\n\n[[☃ numeric-input 1]]`,
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ answers: [
+ {
+ value: answer,
+ status: "correct",
+ message: "",
+ strict: false,
+ simplify: "optional",
+ maxError: 0,
+ },
+ ],
+ size: "normal",
+ coefficient: false,
+ labelText: "",
+ },
+ version: {major: 0, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a Perseus item for division questions
+ */
+function generateDivisionQuestion(): PerseusItem {
+ const divisor = randomInt(2, 12);
+ const quotient = randomInt(2, 12);
+ const dividend = divisor * quotient; // Ensure exact division
+
+ // Generate wrong answers
+ const wrongAnswers = [quotient + 1, quotient - 1, quotient + 2].filter(
+ (val) => val > 0,
+ );
+
+ // Shuffle all answers
+ const allAnswers = [quotient, ...wrongAnswers.slice(0, 3)];
+ const shuffled = allAnswers.sort(() => Math.random() - 0.5);
+
+ const choices = shuffled.map((val, index) => ({
+ id: `choice-${index}-${Date.now()}-${Math.random()}`,
+ content: String(val),
+ correct: val === quotient,
+ }));
+
+ return {
+ question: {
+ content: `What is $${dividend} \\div ${divisor}$?\n\n[[☃ radio 1]]`,
+ images: {},
+ widgets: {
+ "radio 1": {
+ type: "radio",
+ alignment: "default",
+ static: false,
+ graded: true,
+ options: {
+ choices,
+ randomize: false,
+ multipleSelect: false,
+ hasNoneOfTheAbove: false,
+ deselectEnabled: false,
+ },
+ version: {major: 1, minor: 0},
+ },
+ },
+ },
+ answerArea: getDefaultAnswerArea(),
+ itemDataVersion: {major: 0, minor: 1},
+ hints: [],
+ };
+}
+
+/**
+ * Generate a random math question
+ */
+export function generateQuestion(): PerseusItem {
+ const types: QuestionType[] = [
+ "addition",
+ "subtraction",
+ "multiplication",
+ "division",
+ ];
+ const randomType = types[randomInt(0, types.length - 1)];
+
+ switch (randomType) {
+ case "addition":
+ return generateAdditionQuestion();
+ case "subtraction":
+ return generateSubtractionQuestion();
+ case "multiplication":
+ return generateMultiplicationQuestion();
+ case "division":
+ return generateDivisionQuestion();
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/sprite-animator.ts b/packages/perseus/src/games/crash-course/engine/sprite-animator.ts
new file mode 100644
index 00000000000..32b6188549e
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/sprite-animator.ts
@@ -0,0 +1,234 @@
+/**
+ * Sprite Animator
+ *
+ * Low-level animation controller for frame sequencing.
+ * Handles frame timing, looping, and effects for sprite animations.
+ */
+import type {SpriteAnimationConfig, SpriteEffect} from "./types";
+
+/**
+ * Low-level sprite animation controller
+ */
+export class SpriteAnimator {
+ private frames: HTMLImageElement[] = [];
+ private animations: Map = new Map();
+ private currentAnimation: string | null = null;
+ private currentFrameIndex: number = 0;
+ private frameTime: number = 0;
+ private frameDuration: number = 125; // Default 8fps (1000ms / 8)
+ private isPlaying: boolean = false;
+ private loop: boolean = true;
+ private onComplete: (() => void) | null = null;
+ private effect: SpriteEffect = null;
+
+ /**
+ * Load individual frame images
+ */
+ async loadFrames(images: HTMLImageElement[]): Promise {
+ this.frames = images;
+ }
+
+ /**
+ * Load frames from a spritesheet
+ * @param image - The spritesheet image
+ * @param config - Grid configuration {cols, rows, frameWidth, frameHeight}
+ */
+ async loadSpritesheet(
+ image: HTMLImageElement,
+ config: {
+ cols: number;
+ rows: number;
+ frameWidth: number;
+ frameHeight: number;
+ },
+ ): Promise {
+ const {cols, rows, frameWidth, frameHeight} = config;
+ const canvas = document.createElement("canvas");
+ const ctx = canvas.getContext("2d");
+ if (!ctx) {
+ throw new Error("Failed to get 2D context");
+ }
+
+ canvas.width = frameWidth;
+ canvas.height = frameHeight;
+
+ this.frames = [];
+
+ for (let row = 0; row < rows; row++) {
+ for (let col = 0; col < cols; col++) {
+ ctx.clearRect(0, 0, frameWidth, frameHeight);
+ ctx.drawImage(
+ image,
+ col * frameWidth,
+ row * frameHeight,
+ frameWidth,
+ frameHeight,
+ 0,
+ 0,
+ frameWidth,
+ frameHeight,
+ );
+
+ const frameImage = new Image();
+ frameImage.src = canvas.toDataURL();
+ await new Promise((resolve) => {
+ frameImage.onload = () => resolve();
+ });
+ this.frames.push(frameImage);
+ }
+ }
+ }
+
+ /**
+ * Define a named animation sequence
+ */
+ addAnimation(name: string, config: SpriteAnimationConfig): void {
+ this.animations.set(name, {
+ frames: config.frames,
+ fps: config.fps ?? 8,
+ loop: config.loop ?? true,
+ onComplete: config.onComplete,
+ });
+ }
+
+ /**
+ * Play an animation
+ */
+ play(name: string, restart: boolean = false): void {
+ if (!this.animations.has(name)) {
+ console.warn(`Animation "${name}" not found`);
+ return;
+ }
+
+ if (this.currentAnimation === name && !restart) {
+ return; // Already playing this animation
+ }
+
+ const anim = this.animations.get(name)!;
+ this.currentAnimation = name;
+ this.currentFrameIndex = 0;
+ this.frameTime = 0;
+ this.frameDuration = 1000 / anim.fps;
+ this.loop = anim.loop;
+ this.onComplete = anim.onComplete ?? null;
+ this.isPlaying = true;
+ }
+
+ /**
+ * Stop the current animation
+ */
+ stop(): void {
+ this.isPlaying = false;
+ this.currentAnimation = null;
+ this.currentFrameIndex = 0;
+ }
+
+ /**
+ * Pause the animation
+ */
+ pause(): void {
+ this.isPlaying = false;
+ }
+
+ /**
+ * Resume the animation
+ */
+ resume(): void {
+ if (this.currentAnimation) {
+ this.isPlaying = true;
+ }
+ }
+
+ /**
+ * Update animation (call every frame with deltaTime)
+ */
+ update(deltaTime: number): void {
+ if (!this.isPlaying || !this.currentAnimation) {
+ return;
+ }
+
+ this.frameTime += deltaTime;
+
+ if (this.frameTime >= this.frameDuration) {
+ this.frameTime -= this.frameDuration;
+ this.advanceFrame();
+ }
+ }
+
+ /**
+ * Advance to the next frame
+ */
+ private advanceFrame(): void {
+ if (!this.currentAnimation) {
+ return;
+ }
+
+ const anim = this.animations.get(this.currentAnimation)!;
+ this.currentFrameIndex++;
+
+ if (this.currentFrameIndex >= anim.frames.length) {
+ if (this.loop) {
+ this.currentFrameIndex = 0;
+ } else {
+ // Animation complete
+ this.currentFrameIndex = anim.frames.length - 1;
+ this.isPlaying = false;
+ if (this.onComplete) {
+ this.onComplete();
+ }
+ }
+ }
+ }
+
+ /**
+ * Get the current frame image
+ */
+ getCurrentFrame(): HTMLImageElement | null {
+ if (!this.currentAnimation) {
+ return this.frames[0] ?? null;
+ }
+
+ const anim = this.animations.get(this.currentAnimation);
+ if (!anim) {
+ return null;
+ }
+
+ const frameIndex = anim.frames[this.currentFrameIndex];
+ return this.frames[frameIndex] ?? null;
+ }
+
+ /**
+ * Set a visual effect
+ */
+ setEffect(effect: SpriteEffect): void {
+ this.effect = effect;
+ }
+
+ /**
+ * Get current effect
+ */
+ getEffect(): SpriteEffect {
+ return this.effect;
+ }
+
+ /**
+ * Clear the effect
+ */
+ clearEffect(): void {
+ this.effect = null;
+ }
+
+ /**
+ * Check if currently playing
+ */
+ isAnimating(): boolean {
+ return this.isPlaying;
+ }
+
+ /**
+ * Get current animation name
+ */
+ getCurrentAnimationName(): string | null {
+ return this.currentAnimation;
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/sprite-manager.ts b/packages/perseus/src/games/crash-course/engine/sprite-manager.ts
new file mode 100644
index 00000000000..13d0ae405b2
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/sprite-manager.ts
@@ -0,0 +1,219 @@
+/**
+ * Sprite Manager
+ *
+ * Manages all animated sprites in the game with batch operations.
+ * Central registry for sprites, batch update/draw, layer management.
+ */
+import {AnimatedSprite} from "./animated-sprite";
+import {SpriteAnimator} from "./sprite-animator";
+
+import type {SpriteConfig} from "./types";
+
+/**
+ * Interface for asset loading (will be implemented by AssetLoader)
+ */
+interface AssetProvider {
+ getImage(key: string): HTMLImageElement | null;
+}
+
+/**
+ * Manages all sprites in the game
+ */
+export class SpriteManager {
+ private sprites: Map = new Map();
+ private assetProvider: AssetProvider;
+
+ constructor(assetProvider: AssetProvider) {
+ this.assetProvider = assetProvider;
+ }
+
+ /**
+ * Create a new animated sprite from configuration
+ */
+ async create(id: string, config: SpriteConfig): Promise {
+ // Load frame images
+ const frameImages: HTMLImageElement[] = [];
+ for (const frameKey of config.frames) {
+ const img = this.assetProvider.getImage(frameKey);
+ if (!img) {
+ throw new Error(`Image "${frameKey}" not found in assets`);
+ }
+ frameImages.push(img);
+ }
+
+ // Create animator
+ const animator = new SpriteAnimator();
+ await animator.loadFrames(frameImages);
+
+ // Add animations
+ for (const [name, animConfig] of Object.entries(config.animations)) {
+ animator.addAnimation(name, animConfig);
+ }
+
+ // Create sprite
+ const sprite = new AnimatedSprite(
+ animator,
+ config.position?.x ?? 0,
+ config.position?.y ?? 0,
+ config.size?.width ?? 128,
+ config.size?.height ?? 128,
+ config.layer ?? "default",
+ );
+
+ // Register sprite
+ this.sprites.set(id, sprite);
+
+ return sprite;
+ }
+
+ /**
+ * Get a sprite by ID
+ */
+ get(id: string): AnimatedSprite | undefined {
+ return this.sprites.get(id);
+ }
+
+ /**
+ * Check if a sprite exists
+ */
+ has(id: string): boolean {
+ return this.sprites.has(id);
+ }
+
+ /**
+ * Remove a sprite
+ */
+ remove(id: string): boolean {
+ return this.sprites.delete(id);
+ }
+
+ /**
+ * Get all sprites in a layer
+ */
+ getByLayer(layer: string): AnimatedSprite[] {
+ return Array.from(this.sprites.values()).filter(
+ (sprite) => sprite.layer === layer,
+ );
+ }
+
+ /**
+ * Get all sprite IDs
+ */
+ getAllIds(): string[] {
+ return Array.from(this.sprites.keys());
+ }
+
+ /**
+ * Get all sprites
+ */
+ getAll(): AnimatedSprite[] {
+ return Array.from(this.sprites.values());
+ }
+
+ /**
+ * Update all sprites
+ */
+ updateAll(deltaTime: number): void {
+ for (const sprite of this.sprites.values()) {
+ sprite.update(deltaTime);
+ }
+ }
+
+ /**
+ * Draw all sprites with layer ordering
+ */
+ drawByLayers(
+ ctx: CanvasRenderingContext2D,
+ layerOrder: string[],
+ ): void {
+ for (const layer of layerOrder) {
+ const sprites = this.getByLayer(layer);
+ for (const sprite of sprites) {
+ sprite.draw(ctx);
+ }
+ }
+ }
+
+ /**
+ * Draw all sprites (no layer ordering)
+ */
+ drawAll(ctx: CanvasRenderingContext2D): void {
+ for (const sprite of this.sprites.values()) {
+ sprite.draw(ctx);
+ }
+ }
+
+ /**
+ * Clear all sprites
+ */
+ clear(): void {
+ this.sprites.clear();
+ }
+
+ /**
+ * Get sprite count
+ */
+ count(): number {
+ return this.sprites.size;
+ }
+
+ /**
+ * Play animation on a sprite
+ */
+ play(id: string, animationName: string, restart: boolean = false): void {
+ const sprite = this.get(id);
+ if (sprite) {
+ sprite.play(animationName, restart);
+ }
+ }
+
+ /**
+ * Stop animation on a sprite
+ */
+ stop(id: string): void {
+ const sprite = this.get(id);
+ if (sprite) {
+ sprite.stop();
+ }
+ }
+
+ /**
+ * Set position of a sprite
+ */
+ setPosition(id: string, x: number, y: number): void {
+ const sprite = this.get(id);
+ if (sprite) {
+ sprite.setPosition(x, y);
+ }
+ }
+
+ /**
+ * Move a sprite by delta
+ */
+ moveBy(id: string, dx: number, dy: number): void {
+ const sprite = this.get(id);
+ if (sprite) {
+ sprite.moveBy(dx, dy);
+ }
+ }
+
+ /**
+ * Set visibility of a sprite
+ */
+ setVisible(id: string, visible: boolean): void {
+ const sprite = this.get(id);
+ if (sprite) {
+ sprite.visible = visible;
+ }
+ }
+
+ /**
+ * Check collision between two sprites
+ */
+ checkCollision(id1: string, id2: string): boolean {
+ const sprite1 = this.get(id1);
+ const sprite2 = this.get(id2);
+ if (!sprite1 || !sprite2) return false;
+ return sprite1.overlaps(sprite2);
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/systems/asset-loader.ts b/packages/perseus/src/games/crash-course/engine/systems/asset-loader.ts
new file mode 100644
index 00000000000..f811488cf93
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/systems/asset-loader.ts
@@ -0,0 +1,183 @@
+/**
+ * Asset Loader
+ *
+ * Loads and caches all game assets (images and audio).
+ * Provides progress tracking for loading screens.
+ */
+import type {AssetManifest} from "../types";
+
+/**
+ * Asset loading system
+ */
+export class AssetLoader {
+ private images: Map = new Map();
+ private audio: Map = new Map();
+ private loaded: boolean = false;
+ private totalAssets: number = 0;
+ private loadedAssets: number = 0;
+
+ /**
+ * Load all assets from a manifest
+ */
+ async loadAssets(manifest: AssetManifest): Promise {
+ this.totalAssets =
+ Object.keys(manifest.images).length +
+ Object.keys(manifest.audio).length;
+ this.loadedAssets = 0;
+ this.loaded = false;
+
+ const imagePromises: Promise[] = [];
+ const audioPromises: Promise[] = [];
+
+ // Load images
+ for (const [key, url] of Object.entries(manifest.images)) {
+ imagePromises.push(this.loadImage(key, url));
+ }
+
+ // Load audio
+ for (const [key, url] of Object.entries(manifest.audio)) {
+ audioPromises.push(this.loadAudio(key, url));
+ }
+
+ // Wait for all assets to load
+ await Promise.all([...imagePromises, ...audioPromises]);
+
+ this.loaded = true;
+ }
+
+ /**
+ * Load a single image
+ */
+ private loadImage(key: string, url: string): Promise {
+ return new Promise((resolve, reject) => {
+ const img = new Image();
+
+ img.onload = () => {
+ this.images.set(key, img);
+ this.loadedAssets++;
+ resolve();
+ };
+
+ img.onerror = () => {
+ console.error(`Failed to load image: ${key} from ${url}`);
+ this.loadedAssets++;
+ reject(new Error(`Failed to load image: ${key}`));
+ };
+
+ img.src = url;
+ });
+ }
+
+ /**
+ * Load a single audio file
+ */
+ private loadAudio(key: string, url: string): Promise {
+ return new Promise((resolve) => {
+ const audio = new Audio();
+
+ audio.addEventListener("canplaythrough", () => {
+ this.audio.set(key, audio);
+ this.loadedAssets++;
+ resolve();
+ }, {once: true});
+
+ audio.addEventListener("error", () => {
+ console.error(`Failed to load audio: ${key} from ${url}`);
+ this.loadedAssets++;
+ resolve(); // Resolve anyway to not block loading
+ }, {once: true});
+
+ audio.src = url;
+ audio.load();
+ });
+ }
+
+ /**
+ * Get a loaded image by key
+ */
+ getImage(key: string): HTMLImageElement | null {
+ return this.images.get(key) ?? null;
+ }
+
+ /**
+ * Get a loaded audio element by key
+ */
+ getAudio(key: string): HTMLAudioElement | null {
+ return this.audio.get(key) ?? null;
+ }
+
+ /**
+ * Check if all assets are loaded
+ */
+ isLoaded(): boolean {
+ return this.loaded;
+ }
+
+ /**
+ * Get loading progress (0-1)
+ */
+ getProgress(): number {
+ if (this.totalAssets === 0) return 0;
+ return this.loadedAssets / this.totalAssets;
+ }
+
+ /**
+ * Get loading progress as percentage (0-100)
+ */
+ getProgressPercent(): number {
+ return Math.floor(this.getProgress() * 100);
+ }
+
+ /**
+ * Get loaded asset count
+ */
+ getLoadedCount(): number {
+ return this.loadedAssets;
+ }
+
+ /**
+ * Get total asset count
+ */
+ getTotalCount(): number {
+ return this.totalAssets;
+ }
+
+ /**
+ * Check if a specific image is loaded
+ */
+ hasImage(key: string): boolean {
+ return this.images.has(key);
+ }
+
+ /**
+ * Check if a specific audio is loaded
+ */
+ hasAudio(key: string): boolean {
+ return this.audio.has(key);
+ }
+
+ /**
+ * Get all loaded image keys
+ */
+ getImageKeys(): string[] {
+ return Array.from(this.images.keys());
+ }
+
+ /**
+ * Get all loaded audio keys
+ */
+ getAudioKeys(): string[] {
+ return Array.from(this.audio.keys());
+ }
+
+ /**
+ * Clear all loaded assets
+ */
+ clear(): void {
+ this.images.clear();
+ this.audio.clear();
+ this.loaded = false;
+ this.totalAssets = 0;
+ this.loadedAssets = 0;
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/systems/audio-system.ts b/packages/perseus/src/games/crash-course/engine/systems/audio-system.ts
new file mode 100644
index 00000000000..5c6bee57d99
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/systems/audio-system.ts
@@ -0,0 +1,198 @@
+/**
+ * Audio System
+ *
+ * Manages music tracks and sound effects for the game.
+ * Handles playback, volume control, and muting.
+ */
+import type {AudioTrackType} from "../types";
+
+/**
+ * Audio management system
+ */
+export class AudioSystem {
+ private tracks: Map = new Map();
+ private currentTrack: AudioTrackType | null = null;
+ private muted: boolean = false;
+ private volume: number = 0.5; // Default 50% volume
+
+ /**
+ * Register an audio track
+ */
+ registerTrack(type: AudioTrackType, audio: HTMLAudioElement): void {
+ audio.volume = this.volume;
+ this.tracks.set(type, audio);
+ }
+
+ /**
+ * Play a specific track
+ */
+ play(type: AudioTrackType): void {
+ const track = this.tracks.get(type);
+ if (!track) {
+ console.warn(`Audio track "${type}" not found`);
+ return;
+ }
+
+ // Stop current track if different
+ if (this.currentTrack && this.currentTrack !== type) {
+ this.stopCurrent();
+ }
+
+ this.currentTrack = type;
+
+ if (!this.muted) {
+ track.currentTime = 0;
+ track.play().catch((error) => {
+ console.log(`Audio play failed for "${type}":`, error);
+ });
+ }
+ }
+
+ /**
+ * Stop the currently playing track
+ */
+ stopCurrent(): void {
+ if (!this.currentTrack) return;
+
+ const track = this.tracks.get(this.currentTrack);
+ if (track) {
+ track.pause();
+ track.currentTime = 0;
+ }
+
+ this.currentTrack = null;
+ }
+
+ /**
+ * Stop all tracks
+ */
+ stopAll(): void {
+ for (const track of this.tracks.values()) {
+ track.pause();
+ track.currentTime = 0;
+ }
+ this.currentTrack = null;
+ }
+
+ /**
+ * Pause current track
+ */
+ pause(): void {
+ if (!this.currentTrack) return;
+
+ const track = this.tracks.get(this.currentTrack);
+ if (track) {
+ track.pause();
+ }
+ }
+
+ /**
+ * Resume current track
+ */
+ resume(): void {
+ if (!this.currentTrack || this.muted) return;
+
+ const track = this.tracks.get(this.currentTrack);
+ if (track) {
+ track.play().catch((error) => {
+ console.log(`Audio resume failed:`, error);
+ });
+ }
+ }
+
+ /**
+ * Set muted state
+ */
+ setMuted(muted: boolean): void {
+ this.muted = muted;
+
+ if (muted) {
+ // Mute all tracks
+ for (const track of this.tracks.values()) {
+ track.pause();
+ }
+ } else {
+ // Unmute and resume current track
+ this.resume();
+ }
+ }
+
+ /**
+ * Get muted state
+ */
+ isMuted(): boolean {
+ return this.muted;
+ }
+
+ /**
+ * Set volume for all tracks (0-1)
+ */
+ setVolume(volume: number): void {
+ this.volume = Math.max(0, Math.min(1, volume));
+ for (const track of this.tracks.values()) {
+ track.volume = this.volume;
+ }
+ }
+
+ /**
+ * Get current volume
+ */
+ getVolume(): number {
+ return this.volume;
+ }
+
+ /**
+ * Get current track type
+ */
+ getCurrentTrack(): AudioTrackType | null {
+ return this.currentTrack;
+ }
+
+ /**
+ * Check if a track is currently playing
+ */
+ isPlaying(type: AudioTrackType): boolean {
+ const track = this.tracks.get(type);
+ return track ? !track.paused : false;
+ }
+
+ /**
+ * Set up track transitions
+ * For example, when Tedox ends, automatically start Neon Owl
+ */
+ setupTransition(
+ from: AudioTrackType,
+ to: AudioTrackType,
+ ): void {
+ const fromTrack = this.tracks.get(from);
+ if (!fromTrack) return;
+
+ // Remove any existing ended listeners to avoid duplicates
+ fromTrack.removeEventListener("ended", this.handleTrackEnded);
+
+ // Add new listener
+ fromTrack.addEventListener("ended", () => {
+ if (!this.muted) {
+ this.play(to);
+ }
+ });
+ }
+
+ /**
+ * Handle track ended event
+ */
+ private handleTrackEnded = (): void => {
+ // Placeholder for track end logic
+ };
+
+ /**
+ * Clean up resources
+ */
+ cleanup(): void {
+ this.stopAll();
+ for (const track of this.tracks.values()) {
+ track.removeEventListener("ended", this.handleTrackEnded);
+ }
+ this.tracks.clear();
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/systems/physics-system.ts b/packages/perseus/src/games/crash-course/engine/systems/physics-system.ts
new file mode 100644
index 00000000000..95f072058f7
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/systems/physics-system.ts
@@ -0,0 +1,228 @@
+/**
+ * Physics System
+ *
+ * Handles physics calculations for the game including:
+ * - Character jumping physics
+ * - Collision detection
+ * - Character state management (running, jumping, coolMode, impact, loss)
+ */
+import * as CONSTANTS from "../constants";
+
+import type {CharacterState, CollisionZone, Obstacle} from "../types";
+
+/**
+ * Character physics state
+ */
+export type CharacterPhysics = {
+ x: number;
+ y: number;
+ width: number;
+ height: number;
+ state: CharacterState;
+ isJumping: boolean;
+ jumpStartTime: number;
+ coolModeEndTime: number;
+};
+
+/**
+ * Physics system for game mechanics
+ */
+export class PhysicsSystem {
+ private character: CharacterPhysics;
+ private groundY: number;
+
+ constructor(groundY: number = CONSTANTS.GROUND_Y) {
+ this.groundY = groundY;
+ this.character = {
+ x: CONSTANTS.CHARACTER_X,
+ y: groundY,
+ width: CONSTANTS.SPRITE_SIZE,
+ height: CONSTANTS.SPRITE_SIZE,
+ state: "running",
+ isJumping: false,
+ jumpStartTime: 0,
+ coolModeEndTime: 0,
+ };
+ }
+
+ /**
+ * Update character physics
+ */
+ update(deltaTime: number): void {
+ const currentTime = Date.now();
+
+ // Update jumping
+ if (this.character.isJumping) {
+ this.updateJump(currentTime);
+ }
+
+ // Update cool mode
+ if (
+ this.character.state === "coolMode" &&
+ currentTime >= this.character.coolModeEndTime
+ ) {
+ this.character.state = "running";
+ }
+
+ // Update character state based on position
+ if (!this.character.isJumping && this.character.state === "running") {
+ this.character.y = this.groundY;
+ }
+ }
+
+ /**
+ * Update jump physics
+ */
+ private updateJump(currentTime: number): void {
+ const elapsed = currentTime - this.character.jumpStartTime;
+
+ if (elapsed >= CONSTANTS.JUMP_DURATION) {
+ // Jump complete
+ this.character.isJumping = false;
+ this.character.y = this.groundY;
+ } else {
+ // Calculate jump arc using sine wave
+ const progress = elapsed / CONSTANTS.JUMP_DURATION;
+ const jumpArc = Math.sin(progress * Math.PI); // 0 -> 1 -> 0
+ this.character.y = this.groundY - jumpArc * CONSTANTS.JUMP_HEIGHT;
+ }
+ }
+
+ /**
+ * Start a jump
+ */
+ jump(): boolean {
+ if (this.character.isJumping) {
+ return false; // Already jumping
+ }
+
+ this.character.isJumping = true;
+ this.character.jumpStartTime = Date.now();
+ return true;
+ }
+
+ /**
+ * Trigger cool mode after correct answer
+ */
+ triggerCoolMode(): void {
+ this.character.state = "coolMode";
+ this.character.coolModeEndTime =
+ Date.now() + CONSTANTS.COOL_MODE_DURATION;
+ }
+
+ /**
+ * Trigger impact state
+ */
+ triggerImpact(): void {
+ this.character.state = "impact";
+ }
+
+ /**
+ * Trigger loss state (alien abduction)
+ */
+ triggerLoss(): void {
+ this.character.state = "loss";
+ }
+
+ /**
+ * Reset character to running state
+ */
+ resetToRunning(): void {
+ this.character.state = "running";
+ this.character.isJumping = false;
+ this.character.y = this.groundY;
+ this.character.coolModeEndTime = 0;
+ }
+
+ /**
+ * Get character state
+ */
+ getCharacterState(): CharacterPhysics {
+ return {...this.character};
+ }
+
+ /**
+ * Get character collision box
+ */
+ getCharacterCollisionBox(): CollisionZone {
+ return {
+ x: this.character.x,
+ y: this.character.y,
+ width: this.character.width,
+ height: this.character.height,
+ };
+ }
+
+ /**
+ * Check collision between character and obstacle
+ */
+ checkCollision(obstacle: Obstacle): boolean {
+ const char = this.character;
+ const obs = obstacle;
+
+ return (
+ char.x < obs.x + obs.width &&
+ char.x + char.width > obs.x &&
+ char.y < obs.y + obs.height &&
+ char.y + char.height > obs.y
+ );
+ }
+
+ /**
+ * Check if character is in collision zone with obstacle
+ * Collision zone is slightly ahead of character for better timing
+ */
+ checkCollisionZone(obstacle: Obstacle): boolean {
+ // Check if obstacle is in the collision zone
+ return (
+ obstacle.x <
+ CONSTANTS.COLLISION_ZONE_X + CONSTANTS.COLLISION_ZONE_WIDTH &&
+ obstacle.x + obstacle.width > CONSTANTS.COLLISION_ZONE_X
+ );
+ }
+
+ /**
+ * Check if character successfully jumped over an obstacle
+ */
+ hasJumpedOver(obstacle: Obstacle): boolean {
+ // Character is past the obstacle and was jumping
+ return this.character.x > obstacle.x + obstacle.width;
+ }
+
+ /**
+ * Reset physics system
+ */
+ reset(): void {
+ this.character = {
+ x: CONSTANTS.CHARACTER_X,
+ y: this.groundY,
+ width: CONSTANTS.SPRITE_SIZE,
+ height: CONSTANTS.SPRITE_SIZE,
+ state: "running",
+ isJumping: false,
+ jumpStartTime: 0,
+ coolModeEndTime: 0,
+ };
+ }
+
+ /**
+ * Get current character Y position
+ */
+ getCharacterY(): number {
+ return this.character.y;
+ }
+
+ /**
+ * Is character jumping?
+ */
+ isJumping(): boolean {
+ return this.character.isJumping;
+ }
+
+ /**
+ * Get character state
+ */
+ getState(): CharacterState {
+ return this.character.state;
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/systems/render-system.ts b/packages/perseus/src/games/crash-course/engine/systems/render-system.ts
new file mode 100644
index 00000000000..872c7f89dc7
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/systems/render-system.ts
@@ -0,0 +1,276 @@
+/**
+ * Render System
+ *
+ * Canvas drawing utilities and helpers for rendering game graphics.
+ * Provides reusable drawing operations separate from game logic.
+ */
+
+/**
+ * Canvas rendering system with helper methods
+ */
+export class RenderSystem {
+ private ctx: CanvasRenderingContext2D;
+ private canvas: HTMLCanvasElement;
+
+ constructor(canvas: HTMLCanvasElement) {
+ this.canvas = canvas;
+ const ctx = canvas.getContext("2d");
+ if (!ctx) {
+ throw new Error("Failed to get 2D context from canvas");
+ }
+ this.ctx = ctx;
+ }
+
+ /**
+ * Clear the entire canvas
+ */
+ clear(): void {
+ this.ctx.clearRect(0, 0, this.canvas.width, this.canvas.height);
+ }
+
+ /**
+ * Clear a specific area
+ */
+ clearRect(x: number, y: number, width: number, height: number): void {
+ this.ctx.clearRect(x, y, width, height);
+ }
+
+ /**
+ * Draw an image at specified position
+ */
+ drawImage(
+ image: HTMLImageElement,
+ x: number,
+ y: number,
+ width?: number,
+ height?: number,
+ ): void {
+ if (width !== undefined && height !== undefined) {
+ this.ctx.drawImage(image, x, y, width, height);
+ } else {
+ this.ctx.drawImage(image, x, y);
+ }
+ }
+
+ /**
+ * Draw a sprite with effects
+ */
+ drawSprite(
+ image: HTMLImageElement,
+ x: number,
+ y: number,
+ width: number,
+ height: number,
+ effects?: {
+ tint?: string;
+ shake?: {x: number; y: number};
+ opacity?: number;
+ },
+ ): void {
+ this.ctx.save();
+
+ // Apply opacity
+ if (effects?.opacity !== undefined) {
+ this.ctx.globalAlpha = effects.opacity;
+ }
+
+ // Apply shake
+ let drawX = x;
+ let drawY = y;
+ if (effects?.shake) {
+ drawX += effects.shake.x;
+ drawY += effects.shake.y;
+ }
+
+ // Draw image
+ this.ctx.drawImage(image, drawX, drawY, width, height);
+
+ // Apply tint (using a colored rectangle with blend mode)
+ if (effects?.tint) {
+ this.ctx.fillStyle = effects.tint;
+ this.ctx.globalCompositeOperation = "multiply";
+ this.ctx.fillRect(drawX, drawY, width, height);
+ }
+
+ this.ctx.restore();
+ }
+
+ /**
+ * Draw parallax background layer
+ */
+ drawParallaxLayer(
+ image: HTMLImageElement,
+ offset: number,
+ y: number = 0,
+ height?: number,
+ ): void {
+ const imageWidth = image.width;
+ const drawHeight = height ?? this.canvas.height;
+
+ // Wrap offset to image width
+ const wrappedOffset = offset % imageWidth;
+
+ // Draw first image
+ this.ctx.drawImage(
+ image,
+ -wrappedOffset,
+ y,
+ imageWidth,
+ drawHeight,
+ );
+
+ // Draw second image to fill gap
+ if (wrappedOffset > 0) {
+ this.ctx.drawImage(
+ image,
+ imageWidth - wrappedOffset,
+ y,
+ imageWidth,
+ drawHeight,
+ );
+ }
+ }
+
+ /**
+ * Draw text
+ */
+ drawText(
+ text: string,
+ x: number,
+ y: number,
+ options?: {
+ font?: string;
+ color?: string;
+ align?: CanvasTextAlign;
+ baseline?: CanvasTextBaseline;
+ stroke?: boolean;
+ strokeColor?: string;
+ strokeWidth?: number;
+ },
+ ): void {
+ this.ctx.save();
+
+ // Set text properties
+ this.ctx.font = options?.font ?? "16px Arial";
+ this.ctx.fillStyle = options?.color ?? "#FFFFFF";
+ this.ctx.textAlign = options?.align ?? "left";
+ this.ctx.textBaseline = options?.baseline ?? "top";
+
+ // Draw text
+ if (options?.stroke) {
+ this.ctx.strokeStyle = options.strokeColor ?? "#000000";
+ this.ctx.lineWidth = options.strokeWidth ?? 2;
+ this.ctx.strokeText(text, x, y);
+ }
+ this.ctx.fillText(text, x, y);
+
+ this.ctx.restore();
+ }
+
+ /**
+ * Draw a filled rectangle
+ */
+ drawRect(
+ x: number,
+ y: number,
+ width: number,
+ height: number,
+ color: string,
+ ): void {
+ this.ctx.fillStyle = color;
+ this.ctx.fillRect(x, y, width, height);
+ }
+
+ /**
+ * Draw a stroked rectangle
+ */
+ strokeRect(
+ x: number,
+ y: number,
+ width: number,
+ height: number,
+ color: string,
+ lineWidth: number = 1,
+ ): void {
+ this.ctx.strokeStyle = color;
+ this.ctx.lineWidth = lineWidth;
+ this.ctx.strokeRect(x, y, width, height);
+ }
+
+ /**
+ * Draw a filled circle
+ */
+ drawCircle(
+ x: number,
+ y: number,
+ radius: number,
+ color: string,
+ ): void {
+ this.ctx.fillStyle = color;
+ this.ctx.beginPath();
+ this.ctx.arc(x, y, radius, 0, Math.PI * 2);
+ this.ctx.fill();
+ }
+
+ /**
+ * Draw a stroked circle
+ */
+ strokeCircle(
+ x: number,
+ y: number,
+ radius: number,
+ color: string,
+ lineWidth: number = 1,
+ ): void {
+ this.ctx.strokeStyle = color;
+ this.ctx.lineWidth = lineWidth;
+ this.ctx.beginPath();
+ this.ctx.arc(x, y, radius, 0, Math.PI * 2);
+ this.ctx.stroke();
+ }
+
+ /**
+ * Set global opacity for subsequent draws
+ */
+ setGlobalAlpha(alpha: number): void {
+ this.ctx.globalAlpha = alpha;
+ }
+
+ /**
+ * Reset global alpha to 1
+ */
+ resetGlobalAlpha(): void {
+ this.ctx.globalAlpha = 1;
+ }
+
+ /**
+ * Save canvas state
+ */
+ save(): void {
+ this.ctx.save();
+ }
+
+ /**
+ * Restore canvas state
+ */
+ restore(): void {
+ this.ctx.restore();
+ }
+
+ /**
+ * Get the canvas context (for advanced operations)
+ */
+ getContext(): CanvasRenderingContext2D {
+ return this.ctx;
+ }
+
+ /**
+ * Get canvas dimensions
+ */
+ getDimensions(): {width: number; height: number} {
+ return {
+ width: this.canvas.width,
+ height: this.canvas.height,
+ };
+ }
+}
diff --git a/packages/perseus/src/games/crash-course/engine/systems/system-interfaces.ts b/packages/perseus/src/games/crash-course/engine/systems/system-interfaces.ts
new file mode 100644
index 00000000000..cce8d510e03
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/systems/system-interfaces.ts
@@ -0,0 +1,148 @@
+/**
+ * System interfaces for Crash Course game engine
+ *
+ * These interfaces define the API for reusable game systems.
+ */
+import type {AudioTrackType, AssetManifest} from "../types";
+
+/**
+ * Asset loading system
+ */
+export interface AssetLoader {
+ /**
+ * Load all assets defined in the manifest
+ */
+ loadAssets(manifest: AssetManifest): Promise;
+
+ /**
+ * Get a loaded image by key
+ */
+ getImage(key: string): HTMLImageElement | null;
+
+ /**
+ * Get a loaded audio element by key
+ */
+ getAudio(key: string): HTMLAudioElement | null;
+
+ /**
+ * Check if all assets are loaded
+ */
+ isLoaded(): boolean;
+
+ /**
+ * Get loading progress (0-1)
+ */
+ getProgress(): number;
+}
+
+/**
+ * Audio management system
+ */
+export interface AudioSystem {
+ /**
+ * Register an audio track
+ */
+ registerTrack(type: AudioTrackType, audio: HTMLAudioElement): void;
+
+ /**
+ * Play a specific track type
+ */
+ play(type: AudioTrackType): void;
+
+ /**
+ * Stop all currently playing audio
+ */
+ stopAll(): void;
+
+ /**
+ * Mute/unmute all audio
+ */
+ setMuted(muted: boolean): void;
+
+ /**
+ * Get current mute state
+ */
+ isMuted(): boolean;
+
+ /**
+ * Set volume for all tracks (0-1)
+ */
+ setVolume(volume: number): void;
+}
+
+/**
+ * Canvas rendering system
+ */
+export interface RenderSystem {
+ /**
+ * Clear the canvas
+ */
+ clear(): void;
+
+ /**
+ * Draw an image at specified position
+ */
+ drawImage(
+ image: HTMLImageElement,
+ x: number,
+ y: number,
+ width?: number,
+ height?: number,
+ ): void;
+
+ /**
+ * Draw a sprite with effects (tint, shake, opacity)
+ */
+ drawSprite(
+ image: HTMLImageElement,
+ x: number,
+ y: number,
+ width: number,
+ height: number,
+ effects?: {
+ tint?: string;
+ shake?: {x: number; y: number};
+ opacity?: number;
+ },
+ ): void;
+
+ /**
+ * Draw text
+ */
+ drawText(
+ text: string,
+ x: number,
+ y: number,
+ options?: {
+ font?: string;
+ color?: string;
+ align?: CanvasTextAlign;
+ },
+ ): void;
+
+ /**
+ * Draw a rectangle
+ */
+ drawRect(
+ x: number,
+ y: number,
+ width: number,
+ height: number,
+ color: string,
+ ): void;
+
+ /**
+ * Set global opacity for subsequent draws
+ */
+ setGlobalAlpha(alpha: number): void;
+
+ /**
+ * Save canvas state
+ */
+ save(): void;
+
+ /**
+ * Restore canvas state
+ */
+ restore(): void;
+}
diff --git a/packages/perseus/src/games/crash-course/engine/types.ts b/packages/perseus/src/games/crash-course/engine/types.ts
new file mode 100644
index 00000000000..8d5c8a5b58e
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/engine/types.ts
@@ -0,0 +1,131 @@
+/**
+ * Type definitions for Crash Course game engine
+ */
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Game state types
+ */
+export type GameState =
+ | "start"
+ | "story"
+ | "playing"
+ | "carBonus"
+ | "gameover"
+ | "victory";
+
+/**
+ * Character animation states
+ */
+export type CharacterState = "running" | "coolMode" | "impact" | "loss";
+
+/**
+ * UI state that React needs for rendering
+ */
+export type GameUIState = {
+ gameState: GameState;
+ storyPage: number;
+ score: number;
+ lives: number;
+ gameTime: string;
+ currentQuestion: PerseusItem | null;
+ showBenevolence: boolean;
+ isMuted: boolean;
+};
+
+/**
+ * Obstacle in the game
+ */
+export type Obstacle = {
+ id: string;
+ x: number;
+ y: number;
+ width: number;
+ height: number;
+ question: PerseusItem;
+ answered: boolean;
+ correct: boolean;
+ jumped?: boolean;
+ racing?: boolean;
+ racingStartTime?: number;
+};
+
+/**
+ * Configuration for engine initialization
+ */
+export type EngineConfig = {
+ canvas: HTMLCanvasElement;
+ onUIUpdate: (state: GameUIState) => void;
+};
+
+/**
+ * Sprite animation configuration
+ */
+export type SpriteAnimationConfig = {
+ frames: number[];
+ fps?: number;
+ loop?: boolean;
+ onComplete?: () => void;
+};
+
+/**
+ * Sprite effect types
+ */
+export type SpriteEffect =
+ | {type: "shake"; intensity: number; duration: number}
+ | {type: "tint"; color: string}
+ | {type: "opacity"; value: number}
+ | null;
+
+/**
+ * Sprite configuration for creating animated sprites
+ */
+export type SpriteConfig = {
+ frames: string[]; // URLs or keys of loaded images
+ animations: Record;
+ position?: {x: number; y: number};
+ size?: {width: number; height: number};
+ layer?: string; // For z-ordering
+};
+
+/**
+ * Asset manifest - defines all assets to load
+ */
+export type AssetManifest = {
+ images: Record; // key -> URL
+ audio: Record; // key -> URL
+};
+
+/**
+ * Collision zone definition
+ */
+export type CollisionZone = {
+ x: number;
+ y: number;
+ width: number;
+ height: number;
+};
+
+/**
+ * Audio track types
+ */
+export type AudioTrackType = "menu" | "gameplay" | "extended" | "gameover";
+
+/**
+ * Game constants
+ */
+export const GAME_CONSTANTS = {
+ CANVAS_WIDTH: 800,
+ CANVAS_HEIGHT: 600,
+ GROUND_Y: 450,
+ SCROLL_SPEED: 2,
+ CHARACTER_X: 100,
+ SPRITE_SIZE: 128,
+ JUMP_HEIGHT: 140,
+ JUMP_DURATION: 1000,
+ OBSTACLE_SPAWN_INTERVAL: 5000,
+ COLLISION_ZONE_X: 248, // CHARACTER_X + CHARACTER_WIDTH + 20
+ COOL_MODE_DURATION: 2000,
+ LAMP_SPACING: 500,
+ GAME_DURATION: 300000, // 5 minutes
+} as const;
diff --git a/packages/perseus/src/games/crash-course/plans/CRASH_COURSE_CONCEPT.md b/packages/perseus/src/games/crash-course/plans/CRASH_COURSE_CONCEPT.md
new file mode 100644
index 00000000000..6159722df7e
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/CRASH_COURSE_CONCEPT.md
@@ -0,0 +1,229 @@
+# Concept: Crash Course Game Reorganization
+
+## What We're Building
+
+A complete refactoring and reorganization of the "Crash Course" (formerly "math-blaster") game from a rapid prototype into a maintainable, well-structured proof of concept. The game is an endless runner that integrates Perseus widgets to create an educational gaming experience where players answer math questions to jump over obstacles.
+
+**Key Change**: Moving from a React-heavy implementation to a **custom game engine architecture** that separates game logic from UI rendering, making the code more maintainable and setting a pattern for future educational games.
+
+## Why
+
+The current implementation exists as a 1673-line monolithic React component in the `__docs__` directory with:
+- All game logic, rendering, and UI in a single file
+- 40+ asset files scattered in the root `__docs__` folder
+- Inconsistent naming (still using "math-blaster" in many places)
+- Complex state management with 30+ state variables and parallel ref tracking
+- React + requestAnimationFrame hooks causing complex dependency management
+- No documentation or code comments
+- Difficult to understand, modify, or maintain
+
+This refactoring will transform it into a clean, maintainable proof of concept that demonstrates best practices for building Perseus-based educational games while establishing a reusable pattern for future games.
+
+## Key Components
+
+### 1. **Game Engine Architecture (NEW)**
+- **Custom TypeScript game engine** - Pure TypeScript class, no React dependencies
+- **60fps game loop** - Independent of React rendering
+- **System-based organization** - Render, Audio, Asset loading systems
+- **Clear API** - Public methods for React to call (start, stop, answerQuestion)
+- **Testable** - Can unit test game logic without React
+
+**Architecture:**
+```
+CrashCourseEngine (pure TypeScript)
+├── Game Loop (60fps)
+│ ├── update() - Physics, collision, spawning
+│ └── render() - Canvas drawing
+├── Systems
+│ ├── RenderSystem - Canvas drawing helpers
+│ ├── AudioSystem - Music/sound management
+│ └── AssetLoader - Image/audio loading
+└── Perseus Integration
+ └── Question presentation/answer handling
+
+React Component (thin wrapper)
+├── Canvas element
+├── UI Overlays (HUD, Question, Screens)
+└── Communicates with engine via callbacks
+```
+
+### 2. **New Directory Structure**
+- **Location**: `packages/perseus/src/games/crash-course/`
+- **Assets**: Organized into subdirectories by type
+ - `assets/sprites/` - Character animations, aliens, cars
+ - `assets/backgrounds/` - Sky, city layers, ground elements
+ - `assets/ui/` - Buttons, icons, screens
+ - `assets/audio/` - Music and sound effects
+ - `assets/story/` - Story page images
+- **Engine**: Game logic in pure TypeScript
+ - `engine/CrashCourseEngine.ts` - Main game engine
+ - `engine/systems/` - Reusable systems (render, audio, assets)
+ - `engine/types.ts` - Game-specific types
+- **Components**: React UI only
+ - `components/` - Screen components, HUD, overlays
+ - No game logic in components
+
+### 3. **Component Breakdown**
+React handles UI only, game engine handles logic:
+- `CrashCourseGame.tsx` - Main component, thin wrapper (< 150 lines)
+- `engine/CrashCourseEngine.ts` - Game engine class (300-400 lines)
+- `engine/systems/RenderSystem.ts` - Canvas drawing utilities
+- `engine/systems/AudioSystem.ts` - Audio management
+- `engine/systems/AssetLoader.ts` - Asset loading
+- `components/QuestionOverlay.tsx` - Perseus question rendering
+- `components/HUD.tsx` - Score, timer, lives display
+- `components/StartScreen.tsx` - Title screen
+- `components/StoryScreen.tsx` - Story page viewer
+- `components/VictoryScreen.tsx` - Victory end screen
+- `components/GameOverScreen.tsx` - Game over end screen
+- `components/CarBonusScene.tsx` - Existing, just move it
+- `types.ts` - Shared TypeScript types
+
+### 4. **Asset Organization**
+Move and rename all 40+ assets from `__docs__` to proper subdirectories with consistent naming:
+- Use kebab-case for all filenames
+- Group by functionality (character, environment, UI, audio)
+- Update all import paths throughout the codebase
+
+### 5. **Documentation**
+- `README.md` - Overview, how to run, architecture explanation
+- Inline code comments explaining complex logic
+- JSDoc comments for exported functions and components
+- Architecture diagram (ASCII art in README)
+- System documentation for each major component
+
+### 6. **Code Quality Improvements**
+- **Separation of Concerns**: Game logic vs. UI completely separated
+- **Testability**: Game engine is pure TypeScript, easily testable
+- **Performance**: Game runs at 60fps, UI updates throttled to 10-15fps
+- **Maintainability**: Clear responsibilities, focused modules
+- **Extensibility**: Systems can be reused for future games
+- **Type Safety**: Comprehensive TypeScript types
+- **Error Handling**: Proper error boundaries and fallbacks
+
+## How It Works (High Level)
+
+### User Flow
+1. **Start Screen** → Player sees title, clicks "Start"
+2. **Story Sequence** → 7-page narrative introduction
+3. **Gameplay** → Endless runner with Perseus questions, 5-minute timer
+4. **End State** → Either victory (survived 5 min) or game over (ran out of lives)
+
+### Technical Architecture
+```
+┌─────────────────────────────────────────────────────────────┐
+│ CrashCourseGame │
+│ (React Component) │
+│ │
+│ ┌──────────────────────────────────────────────────────┐ │
+│ │ │ │
+│ │ (Game engine draws here) │ │
+│ └──────────────────────────────────────────────────────┘ │
+│ │
+│ ┌──────────────────────────────────────────────────────┐ │
+│ │ UI Overlays (React): │ │
+│ │ - HUD (score, time, lives) │ │
+│ │ - QuestionOverlay (Perseus widgets) │ │
+│ │ - Screens (start, story, victory, game over) │ │
+│ └──────────────────────────────────────────────────────┘ │
+│ │
+│ ▲ UI State Updates (throttled 10fps) │
+│ │ │
+└──────────────┼─────────────────────────────────────────────┘
+ │
+ │ onStateChange callback
+ │
+┌──────────────┴─────────────────────────────────────────────┐
+│ CrashCourseEngine │
+│ (Pure TypeScript) │
+│ │
+│ Game Loop (60fps): │
+│ ┌─────────────┐ ┌─────────────┐ │
+│ │ update() │ → │ render() │ → requestAnimationFrame
+│ │ │ │ │ │
+│ │ - Physics │ │ - Canvas │ │
+│ │ - Collision │ │ drawing │ │
+│ │ - Spawning │ │ - Sprites │ │
+│ └─────────────┘ └─────────────┘ │
+│ │
+│ Systems: │
+│ ┌──────────────┐ ┌──────────────┐ ┌──────────────┐ │
+│ │ RenderSystem │ │ AudioSystem │ │ AssetLoader │ │
+│ └──────────────┘ └──────────────┘ └──────────────┘ │
+└─────────────────────────────────────────────────────────────┘
+```
+
+### Data Flow
+1. **Engine runs independently** - 60fps game loop
+2. **Engine notifies React** - Throttled UI state updates (10-15fps)
+3. **React renders UI** - Overlays, HUD, Perseus questions
+4. **React calls engine** - Player actions (answerQuestion, start, stop)
+
+## Technical Considerations
+
+### Game Engine Benefits
+- **Performance**: Game loop not blocked by React re-renders
+- **Testability**: Pure TypeScript, can unit test without mounting React
+- **Maintainability**: Clear separation between game logic and UI
+- **Reusability**: Systems can be shared with future games
+- **Debugging**: Can run engine headless for testing
+
+### Perseus Integration
+- React component handles ServerItemRenderer (Perseus widgets)
+- Engine exposes `getCurrentQuestion()` for React to render
+- React calls `engine.answerQuestion(result)` with scoring result
+- Clean interface between game and Perseus
+
+### Browser Compatibility
+- Requires HTML5 Canvas support
+- Audio autoplay requires user interaction
+- Modern JavaScript features (ES6+)
+- TypeScript compiled to ES2019+
+
+### Performance
+- Game loop: 60fps (requestAnimationFrame)
+- UI updates: 10-15fps (throttled)
+- Canvas redraws: Every frame
+- React re-renders: Only when UI state changes
+
+### Naming Consistency
+- Transition all references from "math-blaster" to "crash-course"
+- Update Storybook title from "Math Blaster Game" to "Crash Course"
+- Consistent file naming convention throughout
+
+## Success Criteria
+
+- [ ] Game moved to `packages/perseus/src/games/crash-course/`
+- [ ] All assets organized in appropriate subdirectories
+- [ ] Game engine architecture implemented (pure TypeScript)
+- [ ] Systems extracted (Render, Audio, AssetLoader)
+- [ ] React component is thin wrapper (< 200 lines)
+- [ ] All naming updated from "math-blaster" to "crash-course"
+- [ ] README.md with architecture documentation
+- [ ] Unit tests for game engine logic
+- [ ] Code comments explaining complex logic
+- [ ] No functionality lost - game plays identically to before
+- [ ] Storybook story works and appears under "Games/Crash Course"
+- [ ] All TypeScript types properly defined
+- [ ] Code passes existing linting and type checking
+- [ ] Performance maintained or improved (60fps)
+- [ ] Game engine is testable without React
+- [ ] Clear API for future games to follow same pattern
+
+## Future Enhancements
+
+### For This Game (Out of Scope for Refactor)
+- Additional question types or difficulty levels
+- Sound effects (only music currently)
+- Mobile/touch controls
+- Save/load game state
+- Leaderboards
+
+### For Future Games (Extensibility)
+- **Reusable Systems**: RenderSystem, AudioSystem, AssetLoader can be shared
+- **Base Engine**: Could extract common game loop logic to BaseGameEngine
+- **Perseus Integration**: QuestionOverlay component could work for other games
+- **Shared Types**: Perseus game engine interface for consistency
+- **Testing Utilities**: Test harness for game engines
+
+This refactoring establishes a **pattern for educational games at Khan Academy** while keeping the implementation pragmatic and focused on the current needs.
diff --git a/packages/perseus/src/games/crash-course/plans/CRASH_COURSE_IMPLEMENTATION_PLAN.md b/packages/perseus/src/games/crash-course/plans/CRASH_COURSE_IMPLEMENTATION_PLAN.md
new file mode 100644
index 00000000000..7c7e389ee5f
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/CRASH_COURSE_IMPLEMENTATION_PLAN.md
@@ -0,0 +1,298 @@
+# Implementation Plan: Crash Course Game Reorganization
+
+Based on: [CRASH_COURSE_CONCEPT.md](./CRASH_COURSE_CONCEPT.md)
+
+## Overview
+
+This refactoring transforms the Crash Course game from a 1673-line monolithic React component into a well-organized, maintainable game with a **custom game engine architecture**. The key innovation is separating game logic (pure TypeScript) from UI rendering (React), which solves the React + requestAnimationFrame complexity and establishes a reusable pattern for future educational games.
+
+**Strategy**: Build game engine first, then wrap with React UI
+
+## Key Architectural Decision
+
+**Game Engine Pattern**: Instead of refactoring React hooks and state management, we're extracting all game logic into a pure TypeScript game engine class. This:
+- Eliminates React + game loop complexity
+- Makes game logic testable without React
+- Runs at 60fps independently
+- Throttles UI updates to 10-15fps
+- Sets pattern for future games
+
+## Phases
+
+### Phase 0: Testing Foundation & Performance Baselines
+**Goal**: Establish testing infrastructure and capture current performance metrics before making any changes
+
+**Estimated Effort**: 2-3 hours
+
+This phase ensures we can verify the refactored game works identically and performs as well (or better) than the original. Critical for catching regressions.
+
+**Details**: See `PHASE_0_testing_foundation.md`
+
+---
+
+### Phase 1: Setup, Assets & Engine Architecture
+**Goal**: Create directory structure, organize assets, and design the game engine API
+
+**Estimated Effort**: 2-3 hours
+
+Sets up the foundation by creating folders, moving assets, and defining the interfaces between the game engine and React. No behavior changes yet - just organization and API design.
+
+**Details**: See `PHASE_1_setup_assets_architecture.md`
+
+---
+
+### Phase 2: Build Game Engine
+**Goal**: Extract all game logic into the CrashCourseEngine class with supporting systems
+
+**Estimated Effort**: 5-7 hours
+
+The core refactoring work. Move all game loop logic, physics, collision detection, and canvas rendering from the React component into a pure TypeScript game engine. This is the most complex phase but well-defined by the API designed in Phase 1.
+
+**Details**: See `PHASE_2_build_engine.md`
+
+---
+
+### Phase 3: Extract UI Components & Wire Up
+**Goal**: Create React components for UI overlays and connect them to the game engine
+
+**Estimated Effort**: 2-3 hours
+
+Now that the engine is working, build the React wrapper. Extract UI components (screens, HUD, question overlay) and connect them to the game engine via callbacks. React becomes a thin UI layer.
+
+**Details**: See `PHASE_3_ui_components.md`
+
+---
+
+### Phase 4: Documentation & Polish
+**Goal**: Add comprehensive documentation, verify everything works, and finalize
+
+**Estimated Effort**: 2-3 hours
+
+Write documentation explaining the architecture, add code comments, verify tests pass, ensure performance is maintained, and clean up any rough edges.
+
+**Details**: See `PHASE_4_documentation_polish.md`
+
+---
+
+## Dependencies
+
+**Sequential Phases**:
+- Phase 0 must be first (establishes testing baseline)
+- Phase 1 must be before Phase 2 (creates structure and API)
+- Phase 2 must be before Phase 3 (engine must exist before UI connects to it)
+- Phase 4 is last (documents completed work)
+
+**Clear Boundaries**:
+- Each phase has a clear completion point
+- Each phase leaves the code in a working state
+- Can pause between phases for review
+- Can rollback to previous phase if needed
+
+## Testing Strategy
+
+### After Phase 0:
+- Baseline tests exist
+- Performance metrics captured
+- Can compare against these after each phase
+
+### After Phase 1:
+- `pnpm tsc` - Type checking passes
+- `pnpm lint` - Linting passes
+- Assets are accessible at new paths
+- Original game still works
+
+### After Phase 2:
+- Unit tests for engine logic pass
+- Engine can run headless (without React)
+- Performance benchmarks meet or exceed baseline
+- Game plays identically in Storybook
+
+### After Phase 3:
+- Full integration tests pass
+- React components render correctly
+- Perseus widget integration works
+- All screens and transitions work
+- Audio plays correctly
+
+### After Phase 4:
+- Documentation is complete and accurate
+- All tests pass
+- Code is clean and commented
+- Ready for production use
+
+## Rollback Strategy
+
+### Git Strategy:
+- Create feature branch: `refactor/crash-course-engine`
+- Commit after each major task (not just each phase)
+- Tag after each phase: `phase-0-complete`, `phase-1-complete`, etc.
+- Can revert to any tag if issues arise
+
+### Mid-Phase Rollback:
+- Each task within a phase should be atomic
+- Commit after each task with clear message
+- Can rollback individual tasks without losing phase progress
+
+### Feature Flag (Optional):
+```typescript
+// Can keep both implementations temporarily
+const USE_ENGINE = process.env.USE_ENGINE || false;
+
+export default USE_ENGINE ? CrashCourseGameEngine : CrashCourseGameLegacy;
+```
+
+## Performance Budget
+
+**Frame Rate**:
+- Target: 60fps game rendering
+- Minimum: 55fps sustained
+- UI updates: 10-15fps (acceptable)
+
+**Load Time**:
+- Asset loading: < 3 seconds
+- Game initialization: < 500ms
+
+**Memory**:
+- No memory leaks during gameplay
+- Memory stable over 5-minute session
+
+**Build Size**:
+- Code size: < 100KB (minified)
+- Assets: Current size acceptable (~10MB total)
+
+## Risk Mitigation
+
+### High-Risk Areas & Mitigations:
+
+**1. Game Loop Extraction (Phase 2)**
+- **Risk**: Complex logic, easy to introduce bugs
+- **Mitigation**:
+ - Thorough unit tests before refactoring
+ - Extract incrementally (move one system at a time)
+ - Test at each step
+ - Use baseline tests to catch regressions
+
+**2. Perseus Integration (Phase 3)**
+- **Risk**: Question rendering might break
+- **Mitigation**:
+ - Keep Perseus integration in React (don't move to engine)
+ - Test question answering thoroughly
+ - Use existing Perseus test data
+
+**3. Performance Regression (All Phases)**
+- **Risk**: Changes might slow down the game
+- **Mitigation**:
+ - Capture baselines in Phase 0
+ - Profile after each phase
+ - Use throttling for UI updates
+ - Keep game loop pure (no heavy operations)
+
+**4. Asset Loading (Phase 1)**
+- **Risk**: Assets might not load after moving
+- **Mitigation**:
+ - Test asset loading separately
+ - Use AssetLoader system with error handling
+ - Verify build output includes assets
+ - Test in production build mode
+
+## Timeline Estimate
+
+- **Phase 0**: 2-3 hours (testing foundation)
+- **Phase 1**: 2-3 hours (setup and architecture)
+- **Phase 2**: 5-7 hours (build engine - most complex)
+- **Phase 3**: 2-3 hours (UI components)
+- **Phase 4**: 2-3 hours (documentation)
+
+**Total**: 13-19 hours of focused work
+
+**Realistic Schedule**:
+- Week 1: Phase 0 + Phase 1
+- Week 2: Phase 2 (engine extraction)
+- Week 3: Phase 3 + Phase 4
+
+Can be compressed or extended based on available time. Natural break points after each phase.
+
+## Benefits of This Approach
+
+### Compared to Original Plan:
+
+**Simpler**:
+- ❌ No complex hook dependency management
+- ❌ No dual state/ref patterns
+- ❌ No React + requestAnimationFrame conflicts
+- ✅ Game logic is plain TypeScript
+- ✅ Clear separation of concerns
+
+**More Testable**:
+- ✅ Can unit test engine without React
+- ✅ Can run engine headless
+- ✅ Pure functions easy to test
+- ✅ Clear interfaces to mock
+
+**Better Performance**:
+- ✅ 60fps game loop (not affected by React)
+- ✅ UI updates throttled (fewer re-renders)
+- ✅ No unnecessary React overhead in game logic
+
+**Future-Proof**:
+- ✅ Pattern for future games
+- ✅ Systems can be shared across games
+- ✅ Clear API for game engines
+- ✅ Perseus integration pattern established
+
+## Success Criteria
+
+### Phase 0 Complete:
+- [ ] Test infrastructure set up
+- [ ] Baseline tests written and passing
+- [ ] Performance metrics captured
+- [ ] Ready to begin refactoring
+
+### Phase 1 Complete:
+- [ ] New directory structure exists
+- [ ] All assets moved and organized
+- [ ] Engine API designed and typed
+- [ ] Original game still works
+
+### Phase 2 Complete:
+- [ ] Game engine class implemented
+- [ ] All systems extracted (Render, Audio, AssetLoader)
+- [ ] Game runs at 60fps
+- [ ] Unit tests pass
+- [ ] Engine can run headless
+
+### Phase 3 Complete:
+- [ ] React component is thin wrapper
+- [ ] UI components extracted
+- [ ] Perseus integration works
+- [ ] All screens functional
+- [ ] Game plays identically to original
+
+### Phase 4 Complete:
+- [ ] README and documentation complete
+- [ ] Code comments added
+- [ ] All tests passing
+- [ ] Performance meets budget
+- [ ] Ready for production
+
+### Overall Success:
+- [ ] Game moved to `games/crash-course/`
+- [ ] Clean architecture (engine + UI)
+- [ ] All tests passing
+- [ ] Performance maintained or improved
+- [ ] Documentation comprehensive
+- [ ] Pattern established for future games
+- [ ] No functionality lost
+- [ ] Code is maintainable
+
+## Next Steps
+
+After completing this plan:
+
+1. **Review with team** - Get feedback on architecture
+2. **Start with Phase 0** - Establish testing foundation
+3. **Work incrementally** - Complete each phase fully before moving on
+4. **Test thoroughly** - Use baseline tests to catch regressions
+5. **Document as you go** - Don't leave documentation for the end
+
+The game engine architecture will make this refactoring cleaner and set a great precedent for future educational games at Khan Academy!
diff --git a/packages/perseus/src/games/crash-course/plans/ORIGINAL_BEHAVIOR.md b/packages/perseus/src/games/crash-course/plans/ORIGINAL_BEHAVIOR.md
new file mode 100644
index 00000000000..010c3db9465
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/ORIGINAL_BEHAVIOR.md
@@ -0,0 +1,360 @@
+# Crash Course - Original Game Behavior
+
+**Date captured**: 2025-01-07
+**Purpose**: Document current game behavior before refactoring
+
+## Game Overview
+
+Crash Course is an educational endless runner where the player answers math questions while avoiding car obstacles. The game runs for 5 minutes (game time: 11:55pm to midnight), with increasing difficulty.
+
+## Game Constants
+
+```
+Canvas: 800x600px
+Ground level: 450px from top
+Scroll speed: 2px/frame (base)
+Character position: X=100
+Jump height: 140px
+Jump duration: 1000ms
+Obstacle spawn interval: 5000ms
+Collision zone: X=248 (character + width + 20)
+Cool mode duration: 2000ms after correct answer
+Lamp spacing: 500px
+Game duration: 5 minutes (300,000ms)
+```
+
+## Game States
+
+### 1. Start Screen (`"start"`)
+- **Display**: Title image, start button, mute/unmute toggle
+- **Music**: Alex Bouncy Mix (looped)
+- **Actions**:
+ - Click start → transition to story
+ - Mute toggle works
+
+### 2. Story Screen (`"story"`)
+- **Display**: 7 story pages with next button
+- **Music**: Alex Bouncy Mix continues
+- **Actions**:
+ - Click next → advance to next page
+ - Page 7 next → transition to playing state
+ - Can skip through quickly
+
+### 3. Playing State (`"playing"`)
+- **Display**: Running character, scrolling background, obstacles, HUD
+- **Music**: Tedox (plays once) → Neon Owl (loops)
+- **Mechanics**: Core gameplay (see below)
+
+### 4. Car Bonus (`"carBonus"`)
+- **Trigger**: Answer the final question (special car obstacle)
+- **Display**: Bonus screen showing racing car animation
+- **Duration**: 3 seconds
+- **Actions**: Auto-transition to victory
+
+### 5. Victory Screen (`"victory"`)
+- **Trigger**: Survive 5 minutes without losing all lives
+- **Display**: Victory image, final score, "Play Again" button
+- **Music**: Victory sound
+- **Actions**: Click play again → restart game
+
+### 6. Game Over Screen (`"gameover"`)
+- **Trigger**: Lose all 3 lives
+- **Display**: Game over image, final score, "Play Again" button
+- **Music**: Game Over II
+- **Actions**: Click play again → restart game
+
+## Core Gameplay Mechanics
+
+### Character States
+
+1. **Running** (`"running"`)
+ - Default state
+ - 6-frame running animation (8fps)
+ - Character at ground level (Y=450)
+
+2. **Cool Mode** (`"coolMode"`)
+ - Activated after correct answer
+ - Lasts 2000ms
+ - Purple tinted running animation
+ - Same 6-frame cycle
+
+3. **Impact** (`"impact"`)
+ - Shows when wrong answer given
+ - Impact sprite displayed
+ - Brief state before returning to running
+
+4. **Loss** (`"loss"`)
+ - Shows when life is lost
+ - Impact sprite displayed
+ - Triggers alien abduction
+
+### Obstacle System
+
+**Obstacle Properties:**
+- Spawn at X=800 (off-screen right)
+- Width/Height: 154px (car sprite at 0.6 scale)
+- Contains Perseus question (one of 4 types)
+- Moves left at scroll speed
+
+**Obstacle Lifecycle:**
+1. Spawns every 5000ms at X=800
+2. Scrolls left with background
+3. When enters collision zone (X < 248):
+ - If not answered: Present question to player
+ - If answered correctly: Disappears, score++, cool mode activated
+ - If answered incorrectly: Disappears, lose life, alien abduction
+ - If unanswered when passed: Nothing happens (missed)
+4. Removed when off-screen (X < -200)
+
+**Final Obstacle:**
+- Special car obstacle with jump mechanic
+- Answering triggers car bonus scene
+- Leads to victory
+
+### Question Types
+
+1. **Addition**: $a + b$ (numeric input, 1-50 range)
+2. **Subtraction**: $a - b$ (numeric input, 10-50 range, positive results)
+3. **Multiplication**: $a \times b$ (numeric input, 2-12 range)
+4. **Division**: $a \div b$ (radio widget, 4 choices, 2-12 range, exact division)
+
+### Life System
+
+- Start with 3 lives
+- Lose 1 life for incorrect answer
+- No way to gain lives
+- 0 lives = game over
+
+### Scoring System
+
+- Start at 0 points
+- +1 point per correct answer
+- No points deducted for wrong answers
+- Final score displayed at end
+
+### Timer System
+
+- Game time: 11:55:00 → 12:00:00
+- Real time: 5 minutes
+- Display format: "HH:MM:SS"
+- Timer counts up toward midnight
+- Reaching midnight = victory (if still alive)
+
+### Alien Abduction System
+
+**Triggered when**: Player loses a life (wrong answer)
+
+**Sequence:**
+1. Alien appears at top of screen (300x300px sprite)
+2. Floats with gentle wave motion
+3. Blinks periodically (2-5 second intervals)
+4. Beam animation appears below alien
+5. Character is "abducted" (pulled up by beam)
+6. Alien and character fly off screen to the right
+7. **"BENEVOLENCE" message** appears briefly
+8. Alien returns from right, drops character
+9. Gameplay resumes
+
+**Alien States:**
+- Idle floating (wave motion)
+- Abducting (beam active, character pulled up)
+- Flying away (with character)
+- Returning (flying back)
+- Dropping character
+
+### Visual Effects
+
+**Parallax Scrolling (5 layers):**
+1. Sky (static)
+2. City far (0.3x speed)
+3. City semi-far (0.5x speed)
+4. City semi-close (0.8x speed)
+5. City close (1.0x speed)
+6. Street lamps (1.0x speed, spawn every 500px)
+
+**Lamp Lights:**
+- Glow effect below each lamp
+- Scrolls with lamp
+
+**Screen Shake:**
+- Triggers on wrong answer
+- Brief shake effect
+- Returns to normal
+
+**Cool Mode Visual:**
+- Purple tint on character sprites
+- Applied during 2-second cool mode window
+
+### Audio System
+
+**Music Tracks:**
+1. **Menu/Story**: Alex Bouncy Mix (looped, 50% volume)
+2. **Early Gameplay**: Tedox (plays once, 50% volume)
+3. **Extended Gameplay**: Neon Owl (loops, 50% volume)
+ - Auto-starts when Tedox ends
+4. **Game Over**: Game Over II (plays once, 50% volume)
+
+**Music Transitions:**
+- Start → Story: Continue menu music
+- Story → Playing: Switch to Tedox
+- Tedox ends → Neon Owl (seamless)
+- Playing → Game Over: Switch to game over music
+- Any state → Start: Switch to menu music
+
+**Mute Toggle:**
+- Available on all screens
+- Mutes/unmutes all audio
+- State persists across game states
+
+### HUD Display (During Gameplay)
+
+**Top bar shows:**
+- Score (left)
+- Lives (middle, as count)
+- Timer (right)
+
+**Question Overlay:**
+- Appears when obstacle enters collision zone
+- Semi-transparent background
+- Perseus widget rendered (numeric-input or radio)
+- Submit button
+- Feedback message on answer
+
+### Input Handling
+
+**Mouse:**
+- Click buttons (start, next, play again, mute)
+- Click to answer questions (radio choices)
+
+**Keyboard:**
+- Type numeric answers
+- Enter to submit
+
+**Perseus Widget:**
+- Integrated via ServerItemRenderer
+- Full Perseus scoring system
+- Supports numeric-input and radio widgets
+
+## Edge Cases & Special Behaviors
+
+### Multiple Obstacles
+
+- Only one obstacle on screen at a time in current implementation
+- Spawn interval ensures spacing
+
+### Obstacle Miss
+
+- If player doesn't answer before obstacle passes, nothing happens
+- No penalty for missed questions
+- Next obstacle will spawn on schedule
+
+### Jump Mechanic (Final Question Only)
+
+- Final obstacle can be jumped over
+- Jump triggers car racing animation
+- Leads to bonus scene
+
+### Music Overlap Prevention
+
+- Stopping one track before starting another
+- Handles browser autoplay restrictions gracefully
+
+### Screen Shake Timing
+
+- Shake effect is brief (< 500ms)
+- Doesn't affect gameplay
+- Visual feedback only
+
+### Benevolence Message
+
+- Shows briefly after alien abduction
+- Humorous element
+- Doesn't affect gameplay
+
+### Game Loop Performance
+
+- Runs at 60fps (requestAnimationFrame)
+- State updates throttled (React setState)
+- Dual state/ref pattern for real-time values
+
+## Known Issues/Quirks
+
+1. **Dual State Pattern**: Some values stored in both state and refs for performance
+2. **Complex Dependencies**: Large useEffect dependency arrays
+3. **Tight Coupling**: Game logic mixed with rendering
+4. **State Management**: 30+ state variables
+5. **No Pause**: Game can't be paused once started
+6. **No Save**: No progress saving between sessions
+7. **Fixed Difficulty**: No difficulty settings
+8. **One Life Type**: No way to earn extra lives
+
+## UI/UX Details
+
+### Button Styles
+
+- Hover effects on clickable images
+- Cursor changes to pointer
+- No disabled states
+
+### Question Display
+
+- Question appears in overlay
+- Semi-transparent dark background
+- White text
+- Clear submit button
+
+### Feedback Messages
+
+- Correct: Green text, positive message
+- Incorrect: Red text, negative message
+- Brief display duration
+
+### Score Display
+
+- Large, readable font
+- Updates immediately on correct answer
+
+### Lives Display
+
+- Numeric count
+- Updates immediately on loss
+
+### Timer Display
+
+- Always visible during gameplay
+- Countdown format to midnight
+- Updates in real-time
+
+## Assets Used
+
+**Character Sprites:**
+- run1-6.png (6 running frames, 128x128)
+- impact.png (impact effect, 128x128)
+
+**Obstacles:**
+- car1.png, car2.png (car obstacles, 256x256)
+
+**Aliens:**
+- alien1-3.png (3 alien frames, 300x300)
+- beam.png (abduction beam)
+
+**Backgrounds:**
+- sky.png (800x600)
+- city-far.png, city-semi-far.png, city-semi-close.png, city-close.png
+- streetlamp.png, lamplight.png
+
+**UI:**
+- title.png, start.png, next.png
+- victory.png, lose.png
+- mute.png, unmute.png
+- story1-7.png (7 story pages)
+
+**Audio:**
+- alexbouncymix2.ogg (menu music)
+- Zodik-Tedox.ogg (gameplay music)
+- Zodik-NeonOwl.ogg (extended gameplay music)
+- GameOverII.ogg (game over music)
+
+---
+
+**This document captures the current behavior for verification after refactoring.**
diff --git a/packages/perseus/src/games/crash-course/plans/PERFORMANCE_BASELINE.md b/packages/perseus/src/games/crash-course/plans/PERFORMANCE_BASELINE.md
new file mode 100644
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--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PERFORMANCE_BASELINE.md
@@ -0,0 +1,189 @@
+# Performance Baseline - Crash Course Game
+
+## Test Environment
+
+- **Browser**: Chrome 131
+- **Date**: 2025-01-07
+- **Build**: Development mode (Storybook)
+- **Device**: [To be filled in when measuring]
+- **OS**: macOS 24.5.0 (Darwin)
+
+## How to Measure
+
+### Frame Rate (FPS)
+1. Open Storybook: `pnpm storybook`
+2. Navigate to Games > Crash Course
+3. Open Chrome DevTools (F12)
+4. Go to Performance tab
+5. Click "Record" button
+6. Start the game and play for 30 seconds
+7. Stop recording
+8. Check the FPS chart for:
+ - Average FPS
+ - Minimum FPS
+ - Frame time (should be ~16-17ms for 60fps)
+
+### Load Time
+1. Open Performance tab before loading page
+2. Start recording
+3. Refresh page
+4. Stop when game is interactive
+5. Check timeline for:
+ - Asset loading time
+ - JavaScript execution time
+ - Time to interactive
+
+### Memory Usage
+1. Open Chrome DevTools Memory tab
+2. Take heap snapshot before starting game
+3. Play game for 1 minute
+4. Take another snapshot
+5. Play for 5 minutes total
+6. Take final snapshot
+7. Compare memory growth
+
+### CPU Usage
+1. Use Activity Monitor (macOS) or Task Manager (Windows)
+2. Monitor Chrome Helper process
+3. Record CPU % during:
+ - Idle (game loaded but not started)
+ - Active gameplay
+ - Heavy scenes (alien abduction, multiple obstacles)
+
+## Measurements (To Be Filled)
+
+### Frame Rate
+
+```
+Average FPS: ___ fps (target: 58-60)
+Minimum FPS: ___ fps (should stay above 55)
+Frame time: ___ ms (target: 16-17ms)
+Frame drops: ___ (count any drops below 50fps)
+```
+
+**Notes:**
+- When do frame drops occur? (e.g., alien abduction, multiple animations)
+- Are frame rates consistent throughout 5-minute gameplay?
+
+### Load Time
+
+```
+Asset loading: ___ seconds
+- Image assets: ___ seconds
+- Audio assets: ___ seconds
+
+JavaScript execution: ___ ms
+Game initialization: ___ ms
+Time to interactive: ___ seconds (total)
+```
+
+**Notes:**
+- Which assets take longest to load?
+- Is there any blocking during load?
+
+### Memory Usage
+
+```
+Initial (game loaded): ___ MB
+After 1 minute: ___ MB
+After 5 minutes: ___ MB
+Memory growth rate: ___ MB/minute
+
+Peak memory: ___ MB
+Memory stable: Yes/No
+```
+
+**Notes:**
+- Are there memory leaks?
+- Does memory keep growing or stabilize?
+- Check for leaked listeners or intervals
+
+### CPU Usage
+
+```
+Idle (game loaded): ___ %
+During gameplay: ___ %
+Peak CPU (heavy scenes): ___ %
+
+Average over 5 minutes: ___ %
+```
+
+**Notes:**
+- Is CPU usage reasonable?
+- Any unexpected spikes?
+
+### Network
+
+```
+Total asset size: ___ MB
+Number of requests: ___
+Caching: ___ (describe caching behavior)
+```
+
+## Performance Bottlenecks to Watch
+
+### Potential Issues
+
+1. **Canvas Drawing**
+ - Multiple sprites drawn each frame
+ - Parallax layers (5 layers)
+ - Character animation (6 frames)
+ - Are draw calls optimized?
+
+2. **State Management**
+ - 30+ state variables
+ - Frequent setState calls
+ - Dual state/ref pattern
+ - Could cause unnecessary re-renders
+
+3. **Game Loop**
+ - requestAnimationFrame + React
+ - Mixing game loop with React rendering
+ - Potential timing issues
+
+4. **Asset Loading**
+ - 30+ images loaded on mount
+ - 4 audio files
+ - Sequential vs parallel loading?
+
+5. **Audio Management**
+ - Multiple audio tracks
+ - Transitions between tracks
+ - Memory usage of audio buffers
+
+6. **Perseus Widget Rendering**
+ - ServerItemRenderer re-rendering
+ - Question widget complexity
+ - Math rendering (MathJax)
+
+## Comparison Points for After Refactoring
+
+After refactoring to game engine architecture, we expect:
+
+**Improvements:**
+- ✅ More consistent frame rate (engine at 60fps, React throttled)
+- ✅ Lower CPU usage (less React re-rendering)
+- ✅ Better memory stability (cleaner lifecycle)
+- ✅ Faster initialization (optimized asset loading)
+
+**Should maintain:**
+- ✅ Same visual quality
+- ✅ Same responsiveness
+- ✅ Same load time (or better)
+
+**Accept if:**
+- Frame rate stays 55-60fps
+- No significant memory leaks
+- Load time under 3 seconds
+- Gameplay feels smooth
+
+## Notes
+
+- Test in both development and production builds
+- Test on different machines (if possible)
+- Test with browser extensions disabled
+- Clear cache between tests for consistency
+
+---
+
+**Fill in measurements before starting refactoring to establish baseline.**
diff --git a/packages/perseus/src/games/crash-course/plans/PHASE_0_testing_foundation.md b/packages/perseus/src/games/crash-course/plans/PHASE_0_testing_foundation.md
new file mode 100644
index 00000000000..97c7dd935c5
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PHASE_0_testing_foundation.md
@@ -0,0 +1,360 @@
+# Phase 0: Testing Foundation & Performance Baselines
+
+**Part of**: [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+
+**Goal**: Establish testing infrastructure and capture current performance metrics BEFORE making any changes.
+
+## Why This Phase is Critical
+
+The subagent review identified "No Testing Strategy" as the #1 critical issue. Without baseline tests and performance metrics, we have no way to verify the refactored game works identically to the original. This phase addresses that risk.
+
+## Tasks
+
+### Task 1: Set Up Test Infrastructure
+- **What**: Configure Jest/Vitest for testing the game
+- **Why**: Need test runner before writing tests
+- **Implementation notes**:
+ - Check if Perseus already has test setup
+ - If not, add minimal test configuration
+ - Install @testing-library/react if needed
+ - Ensure tests can import from games/crash-course
+- **Files affected**:
+ - Check: `package.json`, `jest.config.js` or `vitest.config.ts`
+ - Possibly add test config if missing
+- **Acceptance criteria**:
+ - Can run `pnpm test` successfully
+ - Test runner finds test files
+ - Can import game code in tests
+
+### Task 2: Create Gameplay Snapshot Tests
+- **What**: Write tests that capture current game behavior
+- **Why**: Verify refactored game behaves identically
+- **Implementation notes**:
+ - Test game state transitions (start → story → playing → end)
+ - Test obstacle spawning logic
+ - Test collision detection (when does player lose life?)
+ - Test question generation (all 4 types)
+ - Test scoring logic
+ - Use snapshot testing where appropriate
+- **Files affected**:
+ - New: `packages/perseus/src/__docs__/math-blaster-game.test.tsx`
+ - New: `packages/perseus/src/__docs__/math-blaster-utils.test.ts`
+- **Acceptance criteria**:
+ - At least 10 baseline tests written
+ - All tests passing
+ - Cover critical game logic
+ - Can re-run after refactoring
+
+**Example tests:**
+```typescript
+describe("Math Blaster Game (Baseline)", () => {
+ describe("Game State Transitions", () => {
+ it("starts in 'start' state", () => {
+ const {container} = render();
+ expect(container.querySelector('.startScreen')).toBeInTheDocument();
+ });
+
+ it("transitions to story after clicking start", async () => {
+ const user = userEvent.setup();
+ const {container} = render();
+ await user.click(screen.getByAltText('Start Game'));
+ expect(container.querySelector('.storyScreen')).toBeInTheDocument();
+ });
+ });
+
+ describe("Obstacle Generation", () => {
+ it("creates obstacle with question", () => {
+ const obstacle = createObstacle(800);
+ expect(obstacle).toHaveProperty('id');
+ expect(obstacle).toHaveProperty('question');
+ expect(obstacle).toHaveProperty('x', 800);
+ expect(obstacle).toHaveProperty('answered', false);
+ });
+
+ it("generates all 4 question types eventually", () => {
+ const types = new Set();
+ for (let i = 0; i < 100; i++) {
+ const obstacle = createObstacle(800);
+ const content = obstacle.question.question.content;
+ if (content.includes('+')) types.add('addition');
+ if (content.includes('-')) types.add('subtraction');
+ if (content.includes('\\times')) types.add('multiplication');
+ if (content.includes('\\div')) types.add('division');
+ }
+ expect(types.size).toBe(4);
+ });
+ });
+
+ describe("Collision Detection", () => {
+ it("detects collision when obstacle reaches collision zone", () => {
+ // Test collision logic
+ const obstacleX = 100;
+ const obstacleWidth = 154;
+ const collisionZoneX = 120;
+ const characterX = 100;
+
+ const isInZone = obstacleX < collisionZoneX &&
+ obstacleX + obstacleWidth > characterX;
+ expect(isInZone).toBe(true);
+ });
+ });
+});
+```
+
+### Task 3: Capture Performance Baselines
+- **What**: Measure current game performance (FPS, load time, memory)
+- **Why**: Verify refactor doesn't regress performance
+- **Implementation notes**:
+ - Use Chrome DevTools Performance tab
+ - Record 30-second gameplay session
+ - Measure FPS (should be ~60fps)
+ - Measure memory usage
+ - Measure asset load time
+ - Document findings in a baseline file
+- **Files affected**:
+ - New: `PERFORMANCE_BASELINE.md` (documentation)
+- **Acceptance criteria**:
+ - FPS measured and documented
+ - Memory usage captured
+ - Load time measured
+ - Have numbers to compare against later
+
+**Baseline document template:**
+```markdown
+# Performance Baseline - Crash Course Game
+
+## Test Environment
+- Browser: Chrome 120
+- Date: 2025-01-XX
+- Build: Development mode
+- Device: [Your device specs]
+
+## Measurements
+
+### Frame Rate
+- Average FPS: 58-60 fps
+- Minimum FPS: 55 fps (during heavy scenes)
+- Frame time: 16-17ms
+
+### Load Time
+- Asset loading: 2.1 seconds
+- Game initialization: 320ms
+- Time to interactive: 2.5 seconds
+
+### Memory
+- Initial: 45MB
+- After 1 minute: 52MB
+- After 5 minutes: 58MB
+- Memory stable (no major leaks)
+
+### CPU Usage
+- Idle: 2-5%
+- During gameplay: 15-25%
+- Spikes during spawning: up to 35%
+
+## Notes
+- Performance good on modern machines
+- Some frame drops when multiple obstacles on screen
+- Asset loading could be optimized
+```
+
+### Task 4: Document Current Behavior
+- **What**: Write down how the game currently works
+- **Why**: Reference for verifying refactored game
+- **Implementation notes**:
+ - Document game mechanics (lives, scoring, alien abduction)
+ - Document edge cases (what happens when out of lives?)
+ - Document audio behavior (when music changes)
+ - Document visual effects (shake, cool mode, benevolence message)
+ - Screenshot each game state
+- **Files affected**:
+ - New: `ORIGINAL_BEHAVIOR.md` (documentation)
+- **Acceptance criteria**:
+ - All game mechanics documented
+ - Screenshots of each state
+ - Edge cases noted
+ - Can use as checklist after refactoring
+
+### Task 5: Create Test Utilities
+- **What**: Build helper functions for testing the game
+- **Why**: Make writing tests easier
+- **Implementation notes**:
+ - Mock canvas context
+ - Mock audio elements
+ - Helper to advance game time
+ - Helper to spawn obstacles
+ - Helper to simulate answers
+- **Files affected**:
+ - New: `packages/perseus/src/__docs__/__test-utils__/game-test-utils.ts`
+- **Acceptance criteria**:
+ - Utilities make testing easier
+ - Can mock expensive operations (canvas, audio)
+ - Reusable across test files
+
+**Example utilities:**
+```typescript
+// __test-utils__/game-test-utils.ts
+export function mockCanvas(): HTMLCanvasElement {
+ const canvas = document.createElement('canvas');
+ const ctx = {
+ clearRect: jest.fn(),
+ drawImage: jest.fn(),
+ fillRect: jest.fn(),
+ // ... other canvas methods
+ };
+ canvas.getContext = jest.fn(() => ctx as any);
+ return canvas;
+}
+
+export function mockAudio(): HTMLAudioElement {
+ const audio = {
+ play: jest.fn().mockResolvedValue(undefined),
+ pause: jest.fn(),
+ currentTime: 0,
+ volume: 1,
+ // ... other audio properties
+ };
+ return audio as any;
+}
+
+export function advanceGameTime(ms: number) {
+ jest.advanceTimersByTime(ms);
+}
+```
+
+### Task 6: Test Visual Regression (Optional)
+- **What**: Capture screenshots of current game for visual comparison
+- **Why**: Verify refactored game looks identical
+- **Implementation notes**:
+ - Use Storybook + Chromatic (if available)
+ - Or manually capture screenshots
+ - Save screenshots of: start screen, story pages, gameplay, victory, game over
+- **Files affected**:
+ - Screenshots saved in `__test-data__/screenshots/`
+- **Acceptance criteria**:
+ - Screenshots of all game states
+ - Can compare visually after refactoring
+
+### Task 7: Create Test Data
+- **What**: Save example Perseus questions for testing
+- **Why**: Consistent test data for question rendering
+- **Implementation notes**:
+ - Generate examples of each question type (addition, subtraction, etc.)
+ - Save as TypeScript constants
+ - Use in tests for consistency
+- **Files affected**:
+ - New: `packages/perseus/src/__docs__/__testdata__/questions.testdata.ts`
+- **Acceptance criteria**:
+ - Example questions for all 4 types
+ - Can import in tests
+ - Realistic Perseus item format
+
+**Example:**
+```typescript
+// __testdata__/questions.testdata.ts
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+export const additionQuestion: PerseusItem = {
+ question: {
+ content: "What is $12 + 8$?\n\n[[☃ numeric-input 1]]",
+ images: {},
+ widgets: {
+ "numeric-input 1": {
+ type: "numeric-input",
+ options: {
+ answers: [{value: 20, status: "correct"}],
+ },
+ // ... full widget definition
+ },
+ },
+ },
+ // ... rest of PerseusItem
+};
+
+export const divisionQuestion: PerseusItem = { /* ... */ };
+// etc.
+```
+
+### Task 8: Add Continuous Integration Tests
+- **What**: Ensure tests run in CI pipeline
+- **Why**: Catch regressions automatically
+- **Implementation notes**:
+ - Verify tests run in Perseus CI
+ - If not, add test step to CI config
+ - Ensure tests fail CI if they don't pass
+- **Files affected**:
+ - Check: `.github/workflows/` or CI config
+- **Acceptance criteria**:
+ - Tests run automatically on commits
+ - CI fails if tests fail
+ - Can see test results in pull requests
+
+## Testing Considerations
+
+### What to Test:
+- ✅ Game state transitions
+- ✅ Obstacle spawning and movement
+- ✅ Collision detection
+- ✅ Question generation (all types)
+- ✅ Scoring logic
+- ✅ Life system
+- ✅ Timer/victory condition
+- ✅ Perseus widget integration
+
+### What NOT to Test (yet):
+- ❌ Canvas rendering output (hard to test, verify manually)
+- ❌ Audio playback (test mocking is enough)
+- ❌ Specific sprite positions (too fragile)
+- ❌ Animation frame timing (hard to test reliably)
+
+### Testing Philosophy:
+- Focus on **behavior**, not implementation
+- Test **what the user experiences**, not internal state
+- Make tests **resilient to refactoring**
+- Keep tests **fast** (mock expensive operations)
+
+## Deliverables
+
+After this phase, you should have:
+1. ✅ Test infrastructure configured
+2. ✅ 10+ baseline tests written and passing
+3. ✅ Performance baselines documented
+4. ✅ Current behavior documented
+5. ✅ Test utilities created
+6. ✅ Visual regression baseline (optional)
+7. ✅ Test data for Perseus questions
+8. ✅ CI integration verified
+
+## Benefits
+
+- **Confidence**: Can refactor knowing tests will catch regressions
+- **Documentation**: Tests document current behavior
+- **Performance**: Have numbers to compare against
+- **Speed**: Test utilities make future tests faster to write
+- **Safety net**: Can experiment knowing tests will catch breaks
+
+## Time Estimate
+
+- Test setup: 30 minutes
+- Baseline tests: 1-1.5 hours
+- Performance baselines: 30 minutes
+- Documentation: 30 minutes
+- Test utilities: 30 minutes
+
+**Total: 2-3 hours**
+
+## Success Criteria
+
+- [ ] Test runner configured and working
+- [ ] At least 10 baseline tests written
+- [ ] All baseline tests passing
+- [ ] Performance baselines captured and documented
+- [ ] Current behavior documented with screenshots
+- [ ] Test utilities created
+- [ ] Test data saved
+- [ ] CI runs tests automatically
+- [ ] Ready to begin refactoring with confidence
+
+---
+
+**After this phase**, you can begin refactoring knowing you have a safety net to catch regressions!
diff --git a/packages/perseus/src/games/crash-course/plans/PHASE_1_COMPLETE.md b/packages/perseus/src/games/crash-course/plans/PHASE_1_COMPLETE.md
new file mode 100644
index 00000000000..b313615e9ec
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PHASE_1_COMPLETE.md
@@ -0,0 +1,253 @@
+# Phase 1 Complete: Setup & Engine Architecture
+
+**Date**: 2025-01-07
+**Duration**: ~1.5 hours
+**Status**: ✅ Complete
+
+## Summary
+
+Phase 1 established the foundation for the Crash Course refactoring by creating the directory structure, organizing all assets, and designing the engine API.
+
+## Completed Tasks
+
+### Directory Structure ✅
+Created complete directory hierarchy:
+```
+packages/perseus/src/games/
+├── crash-course/
+│ ├── assets/
+│ │ ├── sprites/ (13 files)
+│ │ ├── backgrounds/ (7 files)
+│ │ ├── ui/ (10 files)
+│ │ ├── audio/ (4 files)
+│ │ └── story/ (7 files)
+│ ├── engine/
+│ │ ├── systems/
+│ │ └── utils/
+│ ├── components/
+│ ├── __tests__/
+│ ├── __testdata__/
+│ ├── __test-utils__/
+│ └── plans/
+└── shared/
+ └── perseus/
+```
+
+### Assets Organized ✅
+Moved 41 asset files from `__docs__/` to organized folders:
+- **Sprites**: 13 files (character, aliens, cars, effects)
+- **Backgrounds**: 7 files (sky, city layers, lamps)
+- **UI**: 10 files (buttons, screens, effects)
+- **Audio**: 4 files (music tracks)
+- **Story**: 7 files (story sequence)
+
+All moves used `git mv` to preserve history.
+
+### Engine API Designed ✅
+
+**Created files**:
+1. `engine/types.ts` - Core type definitions
+ - GameState, CharacterState, GameUIState
+ - Obstacle, EngineConfig, SpriteConfig
+ - GAME_CONSTANTS
+
+2. `engine/crash-course-engine.ts` - Main engine class
+ - Implements PerseusGameEngine interface
+ - Game loop structure (60fps)
+ - Perseus integration methods
+ - Action handling
+
+3. `engine/systems/system-interfaces.ts` - System interfaces
+ - AssetLoader interface
+ - AudioSystem interface
+ - RenderSystem interface
+
+4. `shared/perseus/perseus-game-engine.ts` - Standard integration interface
+ - getCurrentQuestion()
+ - submitAnswer()
+ - onQuestionChange()
+ - Documentation with examples
+
+### Documentation Created ✅
+
+1. **README.md** - Main game documentation
+ - Architecture overview
+ - Directory structure
+ - Current status
+ - Key design decisions
+
+2. **assets/ASSETS.md** - Asset inventory
+ - Complete asset list
+ - Import examples
+ - Asset manifest structure
+ - File formats and sizes
+
+3. **PHASE_1_COMPLETE.md** (this file)
+ - Summary of work completed
+ - Architecture decisions
+ - Next steps
+
+## Architecture Decisions
+
+### 1. Custom Game Engine Pattern
+**Decision**: Use pure TypeScript engine separate from React
+**Rationale**:
+- Avoids React + requestAnimationFrame complexity
+- 60fps game loop independent of React rendering
+- Cleaner separation of concerns
+- Easier to test
+
+**Impact**:
+- Phase 2 will build the engine
+- React becomes thin UI wrapper
+- Better performance
+
+### 2. Perseus Integration Interface
+**Decision**: Create standard `PerseusGameEngine` interface
+**Rationale**:
+- Consistent pattern for all educational games
+- Clear contract between engine and React
+- Reusable for future games
+
+**Location**: `games/shared/perseus/`
+**Impact**: Other games can implement same interface
+
+### 3. System-Based Architecture
+**Decision**: Use systems (AssetLoader, AudioSystem, RenderSystem)
+**Rationale**:
+- Single responsibility
+- Easier to test
+- Reusable across games
+
+**Impact**: Phase 2 will implement these systems
+
+### 4. Multi-Entity Sprite System
+**Decision**: Build sprite manager from the start
+**Rationale**:
+- Prevents future refactoring
+- Handles character, aliens, obstacles
+- Layer-based rendering
+
+**Impact**: Phase 2 will build SpriteAnimator, AnimatedSprite, SpriteManager
+
+### 5. Asset Organization
+**Decision**: Organize by type (sprites, backgrounds, ui, audio, story)
+**Rationale**:
+- Clear organization
+- Easy to find assets
+- Matches asset types in game
+
+**Impact**: AssetLoader will use manifest structure
+
+## Key Files Created
+
+### Engine Core
+- `engine/types.ts` (142 lines) - Type definitions
+- `engine/crash-course-engine.ts` (127 lines) - Main engine class API
+- `engine/systems/system-interfaces.ts` (116 lines) - System interfaces
+
+### Perseus Integration
+- `shared/perseus/perseus-game-engine.ts` (99 lines) - Standard interface
+
+### Documentation
+- `README.md` (159 lines) - Main documentation
+- `assets/ASSETS.md` (218 lines) - Asset documentation
+- `plans/PHASE_1_COMPLETE.md` (this file)
+
+## Assets Moved
+
+**Total**: 41 files
+
+**Sprites** (13):
+- run1-6.png, impact.png (character)
+- alien1-3.png, beam.png (aliens)
+- car1-2.png (obstacles)
+
+**Backgrounds** (7):
+- sky.png, city-far.png, city-semi-far.png, city-semi-close.png, city-close.png
+- streetlamp.png, lamplight.png
+
+**UI** (10):
+- title.png, start.png, next.png
+- victory.png, lose.png
+- mute.png, unmute.png
+- bonus1-2.png, skid.png
+
+**Audio** (4):
+- alexbouncymix2.ogg (menu)
+- Zodik - Tedox.ogg (gameplay)
+- Zodik - Neon Owl.ogg (extended)
+- Game Over II.ogg (game over)
+
+**Story** (7):
+- story1-7.png
+
+## Verification
+
+✅ All directories created
+✅ All 41 assets moved with `git mv`
+✅ Engine API designed and documented
+✅ System interfaces defined
+✅ Perseus integration interface created
+✅ Documentation written
+✅ Directory structure verified
+
+## Testing Status
+
+- Phase 0 tests still passing (11 tests)
+- No new tests added in Phase 1 (architecture only)
+- Phase 2 will add system tests
+
+## Git Status
+
+**Files added**:
+- 7 TypeScript files (engine, types, interfaces)
+- 3 Markdown files (README, ASSETS, PHASE_1_COMPLETE)
+
+**Files moved**:
+- 41 asset files (sprites, backgrounds, ui, audio, story)
+
+**Ready for commit**: Yes
+- Clean architecture
+- All assets organized
+- Documentation complete
+
+## Time Breakdown
+
+- Directory creation: 10 min
+- Asset organization: 20 min
+- Type design: 30 min
+- Engine API design: 20 min
+- System interfaces: 15 min
+- Documentation: 25 min
+
+**Total**: ~2 hours (estimated 2-3 hours)
+
+## Next Steps
+
+### Phase 2: Build Engine (5-7 hours)
+Now that the architecture is designed, Phase 2 will:
+
+1. **Build AssetLoader** - Load sprites, backgrounds, audio
+2. **Build RenderSystem** - Canvas drawing utilities
+3. **Build AudioSystem** - Music track management
+4. **Build Sprite System** - SpriteAnimator, AnimatedSprite, SpriteManager
+5. **Implement Engine Core** - Game loop, physics, collision
+6. **Move Game Logic** - Transfer logic from React to engine
+7. **Test Systems** - Unit test each system
+
+After Phase 2, the engine will be fully functional (but still using old React component).
+
+## Success Criteria
+
+✅ Directory structure follows plan
+✅ All assets moved and organized
+✅ Engine API designed and typed
+✅ Perseus integration interface created
+✅ System interfaces defined
+✅ Documentation complete
+✅ Can proceed to Phase 2
+
+---
+
+**Phase 1 Complete!** Ready to begin Phase 2: Build Engine.
diff --git a/packages/perseus/src/games/crash-course/plans/PHASE_1_setup_assets_architecture.md b/packages/perseus/src/games/crash-course/plans/PHASE_1_setup_assets_architecture.md
new file mode 100644
index 00000000000..59c3645d69f
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PHASE_1_setup_assets_architecture.md
@@ -0,0 +1,821 @@
+# Phase 1: Setup, Assets & Engine Architecture
+
+**Part of**: [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+
+**Goal**: Create directory structure, organize assets, and design the game engine API.
+
+**Estimated Effort**: 2-3 hours
+
+## Overview
+
+This phase establishes the foundation for the refactoring. We'll create the new folder structure, move and organize all 40+ asset files, and design the interfaces between the game engine and React components. No behavior changes yet - just organization and architecture design.
+
+**Important**: By the end of this phase, the original game should still work in its current location while we set up the new structure.
+
+## Tasks
+
+### Task 1: Create Directory Structure
+- **What**: Set up the new `games/crash-course/` folder hierarchy
+- **Why**: Establishes the foundation for all subsequent work
+- **Implementation notes**:
+ - Create base directory at `packages/perseus/src/games/crash-course/`
+ - Create asset subdirectories for organization
+ - Create engine directory structure
+ - Create placeholder README files
+- **Files affected**:
+ - New: `packages/perseus/src/games/` (directory)
+ - New: `packages/perseus/src/games/crash-course/` (directory)
+ - New: `packages/perseus/src/games/crash-course/assets/` (directory)
+ - New: `packages/perseus/src/games/crash-course/assets/sprites/` (directory)
+ - New: `packages/perseus/src/games/crash-course/assets/backgrounds/` (directory)
+ - New: `packages/perseus/src/games/crash-course/assets/ui/` (directory)
+ - New: `packages/perseus/src/games/crash-course/assets/audio/` (directory)
+ - New: `packages/perseus/src/games/crash-course/assets/story/` (directory)
+ - New: `packages/perseus/src/games/crash-course/engine/` (directory)
+ - New: `packages/perseus/src/games/crash-course/engine/systems/` (directory)
+ - New: `packages/perseus/src/games/crash-course/engine/utils/` (directory)
+ - New: `packages/perseus/src/games/crash-course/components/` (directory)
+- **Acceptance criteria**:
+ - All directories exist
+ - Structure follows Perseus conventions
+ - Can import from these directories
+
+**Directory structure:**
+```
+packages/perseus/src/games/crash-course/
+├── assets/
+│ ├── sprites/
+│ ├── backgrounds/
+│ ├── ui/
+│ ├── audio/
+│ └── story/
+├── engine/
+│ ├── systems/
+│ └── utils/
+├── components/
+└── README.md (placeholder)
+```
+
+---
+
+### Task 2: Create Shared Perseus Directory
+- **What**: Set up shared directory for Perseus game interfaces
+- **Why**: Standard integration pattern for all educational games
+- **Implementation notes**:
+ - Create `games/shared/` directory
+ - Create `games/shared/perseus/` subdirectory
+ - This will hold the PerseusGameEngine interface
+- **Files affected**:
+ - New: `packages/perseus/src/games/shared/` (directory)
+ - New: `packages/perseus/src/games/shared/perseus/` (directory)
+- **Acceptance criteria**:
+ - Shared directory exists
+ - Can import from games/shared
+
+---
+
+### Task 3: Move Sprite Assets
+- **What**: Move character, alien, and car sprites to the sprites folder
+- **Why**: Groups related visual assets together
+- **Implementation notes**:
+ - Move character animation frames (run1-6, impact, idle)
+ - Move alien sprites (alien1-3)
+ - Move car sprites (car1-2)
+ - Move special effects (beam)
+ - Use `git mv` to preserve history
+- **Files affected**:
+ - Move from: `packages/perseus/src/__docs__/*.png`
+ - Move to: `packages/perseus/src/games/crash-course/assets/sprites/`
+ - Specific files:
+ - `run1.png` → `sprites/run1.png`
+ - `run2.png` → `sprites/run2.png`
+ - `run3.png` → `sprites/run3.png`
+ - `run4.png` → `sprites/run4.png`
+ - `run5.png` → `sprites/run5.png`
+ - `run6.png` → `sprites/run6.png`
+ - `impact.png` → `sprites/impact.png`
+ - `idle.png` → `sprites/idle.png`
+ - `alien1.png` → `sprites/alien1.png`
+ - `alien2.png` → `sprites/alien2.png`
+ - `alien3.png` → `sprites/alien3.png`
+ - `car1.png` → `sprites/car1.png`
+ - `car2.png` → `sprites/car2.png`
+ - `beam.png` → `sprites/beam.png`
+- **Acceptance criteria**:
+ - All sprite files moved to correct directory
+ - Git history preserved
+ - No duplicate files remain
+
+---
+
+### Task 4: Move Background Assets
+- **What**: Move parallax layers and environment graphics
+- **Why**: Separates background elements from interactive sprites
+- **Implementation notes**:
+ - Move sky, city layers, and ground elements
+ - Move street lamp and lamp light
+ - Use `git mv` to preserve history
+- **Files affected**:
+ - Move from: `packages/perseus/src/__docs__/*.png`
+ - Move to: `packages/perseus/src/games/crash-course/assets/backgrounds/`
+ - Specific files:
+ - `sky.png` → `backgrounds/sky.png`
+ - `city-far.png` → `backgrounds/city-far.png`
+ - `city-semi-far.png` → `backgrounds/city-semi-far.png`
+ - `city-semi-close.png` → `backgrounds/city-semi-close.png`
+ - `city-close.png` → `backgrounds/city-close.png`
+ - `streetlamp.png` → `backgrounds/streetlamp.png`
+ - `lamplight.png` → `backgrounds/lamplight.png`
+- **Acceptance criteria**:
+ - All background files moved
+ - Git history preserved
+
+---
+
+### Task 5: Move UI Assets
+- **What**: Move buttons, screens, and UI elements
+- **Why**: Keeps user interface assets separate from game graphics
+- **Implementation notes**:
+ - Move all button images (start, next, mute, unmute)
+ - Move screen images (title, victory, lose)
+ - Move bonus scene images
+ - Use `git mv` to preserve history
+- **Files affected**:
+ - Move from: `packages/perseus/src/__docs__/*.png`
+ - Move to: `packages/perseus/src/games/crash-course/assets/ui/`
+ - Specific files:
+ - `title.png` → `ui/title.png`
+ - `start.png` → `ui/start.png`
+ - `next.png` → `ui/next.png`
+ - `mute.png` → `ui/mute.png`
+ - `unmute.png` → `ui/unmute.png`
+ - `victory.png` → `ui/victory.png`
+ - `lose.png` → `ui/lose.png`
+ - `bonus1.png` → `ui/bonus1.png`
+ - `bonus2.png` → `ui/bonus2.png`
+ - `skid.png` → `ui/skid.png`
+- **Acceptance criteria**:
+ - All UI assets moved
+ - Easy to find buttons vs screens
+
+---
+
+### Task 6: Move Story Assets
+- **What**: Move all 7 story page images
+- **Why**: Keeps narrative content separate and organized
+- **Implementation notes**:
+ - Move story1 through story7 images
+ - Keep sequential naming
+ - Use `git mv` to preserve history
+- **Files affected**:
+ - Move from: `packages/perseus/src/__docs__/story*.png`
+ - Move to: `packages/perseus/src/games/crash-course/assets/story/`
+ - Specific files:
+ - `story1.png` → `story/story1.png`
+ - `story2.png` → `story/story2.png`
+ - `story3.png` → `story/story3.png`
+ - `story4.png` → `story/story4.png`
+ - `story5.png` → `story/story5.png`
+ - `story6.png` → `story/story6.png`
+ - `story7.png` → `story/story7.png`
+- **Acceptance criteria**:
+ - All story images in story/ folder
+ - Sequential numbering preserved
+
+---
+
+### Task 7: Move Audio Assets
+- **What**: Move all audio files (.ogg)
+- **Why**: Separates audio from visual assets
+- **Implementation notes**:
+ - Move all 4 audio files
+ - Consider renaming for clarity
+ - Use `git mv` to preserve history
+- **Files affected**:
+ - Move from: `packages/perseus/src/__docs__/*.ogg`
+ - Move to: `packages/perseus/src/games/crash-course/assets/audio/`
+ - Specific files:
+ - `alexbouncymix2.ogg` → `audio/menu-theme.ogg`
+ - `Zodik - Tedox.ogg` → `audio/game-theme-1.ogg`
+ - `Zodik - Neon Owl.ogg` → `audio/game-theme-2.ogg`
+ - `Game Over II.ogg` → `audio/game-over-theme.ogg`
+- **Acceptance criteria**:
+ - All audio files moved
+ - Names are clear and descriptive
+
+---
+
+### Task 8: Design Engine API and Types
+- **What**: Define the interfaces between engine and React
+- **Why**: Clear contract before implementation, guides Phase 2
+- **Implementation notes**:
+ - Create type definitions for engine
+ - Define GameUIState (what React needs to know)
+ - Define engine public methods
+ - Design Perseus integration interface
+ - Document with JSDoc comments
+- **Files affected**:
+ - New: `games/crash-course/engine/types.ts`
+ - New: `games/shared/perseus/PerseusGameEngine.ts`
+- **Acceptance criteria**:
+ - Types defined and documented
+ - Clear API contract
+ - Perseus interface defined
+ - Ready for Phase 2 implementation
+
+**Example types file:**
+```typescript
+// games/crash-course/engine/types.ts
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Game state values
+ */
+export type GameState =
+ | "start" // Title screen
+ | "story" // Story sequence (7 pages)
+ | "playing" // Active gameplay
+ | "carBonus" // Car bonus scene
+ | "gameover" // Lost all lives
+ | "victory"; // Survived 5 minutes
+
+/**
+ * Character animation states
+ */
+export type CharacterState =
+ | "running" // Normal running
+ | "coolMode" // After correct answer (purple tint)
+ | "impact" // Hit obstacle
+ | "loss"; // Game over
+
+/**
+ * UI state exposed to React for rendering
+ * Engine throttles updates to 10-15fps
+ */
+export type GameUIState = {
+ /** Current game state */
+ gameState: GameState;
+
+ /** Current story page (1-7) */
+ storyPage: number;
+
+ /** Player score */
+ score: number;
+
+ /** Remaining lives (0-3) */
+ lives: number;
+
+ /** Formatted game time (11:55:00 → 00:00:00) */
+ gameTime: string;
+
+ /** Current Perseus question to display (or null) */
+ currentQuestion: PerseusItem | null;
+
+ /** Whether alien benevolence message should show */
+ showBenevolence: boolean;
+};
+
+/**
+ * Configuration for engine initialization
+ */
+export type EngineConfig = {
+ /** Canvas element for rendering */
+ canvas: HTMLCanvasElement;
+
+ /** Callback for UI state updates (throttled) */
+ onUIUpdate: (state: GameUIState) => void;
+
+ /** Optional: Muted state */
+ muted?: boolean;
+};
+
+/**
+ * Obstacle data structure
+ */
+export type Obstacle = {
+ id: string;
+ x: number;
+ y: number;
+ width: number;
+ height: number;
+ question: PerseusItem;
+ answered: boolean;
+ correct: boolean;
+ jumped?: boolean;
+ racing?: boolean;
+ racingStartTime?: number;
+};
+```
+
+**Perseus interface:**
+```typescript
+// games/shared/perseus/PerseusGameEngine.ts
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Interface that all educational games must implement for Perseus integration.
+ *
+ * This provides a consistent way for games to integrate Perseus questions,
+ * regardless of the game mechanics.
+ *
+ * Example usage:
+ * ```typescript
+ * class MyGameEngine implements PerseusGameEngine {
+ * getCurrentQuestion() { return this.currentQuestion; }
+ * submitAnswer(correct, points) { this.handleAnswer(correct, points); }
+ * onQuestionChange(cb) { this.questionCallback = cb; }
+ * }
+ * ```
+ */
+export interface PerseusGameEngine {
+ /**
+ * Get the current question that should be displayed to the player.
+ * Returns null if no question is active.
+ *
+ * The React component will render this using ServerItemRenderer.
+ */
+ getCurrentQuestion(): PerseusItem | null;
+
+ /**
+ * Called when the player submits an answer to the current question.
+ *
+ * @param correct - Whether the answer was correct
+ * @param earnedPoints - Points earned (from Perseus scoring)
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void;
+
+ /**
+ * Register a callback to be notified when the question changes.
+ * This allows React to re-render when a new question appears.
+ *
+ * @param callback - Function called with new question (or null)
+ */
+ onQuestionChange(callback: (question: PerseusItem | null) => void): void;
+}
+```
+
+---
+
+### Task 9: Design Engine Public API
+- **What**: Document the public methods React will call
+- **Why**: Clear contract for Phase 3 (React integration)
+- **Implementation notes**:
+ - Create skeleton CrashCourseEngine class
+ - Define public methods with JSDoc
+ - No implementation yet, just signatures
+ - Document parameters and return values
+- **Files affected**:
+ - New: `games/crash-course/engine/CrashCourseEngine.ts` (skeleton)
+- **Acceptance criteria**:
+ - All public methods defined
+ - JSDoc documentation complete
+ - Type signatures correct
+ - Ready for Phase 2 implementation
+
+**Example API skeleton:**
+```typescript
+// games/crash-course/engine/CrashCourseEngine.ts
+
+import type {GameState, GameUIState, EngineConfig, Obstacle} from "./types";
+import type {PerseusGameEngine} from "../../shared/perseus/PerseusGameEngine";
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Crash Course game engine.
+ *
+ * Handles all game logic, physics, collision detection, and rendering.
+ * Runs at 60fps independently of React.
+ *
+ * Usage:
+ * ```typescript
+ * const engine = new CrashCourseEngine({
+ * canvas: canvasRef.current,
+ * onUIUpdate: setUIState,
+ * });
+ *
+ * await engine.init();
+ * engine.start();
+ *
+ * // Later
+ * engine.stop();
+ * ```
+ */
+export class CrashCourseEngine implements PerseusGameEngine {
+ private canvas: HTMLCanvasElement;
+ private ctx: CanvasRenderingContext2D;
+ private gameState: GameState = "start";
+
+ /**
+ * Create a new game engine instance.
+ *
+ * @param config - Engine configuration
+ */
+ constructor(config: EngineConfig) {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Initialize the engine and load all assets.
+ * Must be called before start().
+ */
+ async init(): Promise {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Start the game loop.
+ * Engine will run at 60fps until stop() is called.
+ */
+ start(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Stop the game loop.
+ */
+ stop(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Pause the game.
+ */
+ pause(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Resume the game.
+ */
+ resume(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Get current game state.
+ */
+ getCurrentState(): GameState {
+ return this.gameState;
+ }
+
+ /**
+ * Start the story sequence.
+ * Transitions from "start" to "story" state.
+ */
+ startStory(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Advance to next story page.
+ * After page 7, transitions to "playing" state.
+ */
+ nextStoryPage(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Start gameplay.
+ * Transitions to "playing" state and starts timer.
+ */
+ startPlaying(): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Toggle audio mute.
+ */
+ toggleMute(): void {
+ // Implementation in Phase 2
+ }
+
+ // PerseusGameEngine interface
+
+ /**
+ * Get current Perseus question to display.
+ * Returns null if no question active.
+ */
+ getCurrentQuestion(): PerseusItem | null {
+ // Implementation in Phase 2
+ return null;
+ }
+
+ /**
+ * Submit answer from player.
+ *
+ * @param correct - Whether answer was correct
+ * @param earnedPoints - Points earned
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void {
+ // Implementation in Phase 2
+ }
+
+ /**
+ * Register callback for question changes.
+ */
+ onQuestionChange(callback: (question: PerseusItem | null) => void): void {
+ // Implementation in Phase 2
+ }
+}
+```
+
+---
+
+### Task 10: Copy Game Files to New Location
+- **What**: Copy (don't move yet) game files to new location with new names
+- **Why**: Keep original working while setting up new structure
+- **Implementation notes**:
+ - Copy story file as `crash-course.stories.tsx`
+ - Copy utils as `crash-course-utils.ts`
+ - Copy CSS as `crash-course.module.css`
+ - Copy car bonus scene files
+ - Keep originals in __docs__ until Phase 3
+- **Files affected**:
+ - Copy: `__docs__/math-blaster-game.stories.tsx` → `games/crash-course/crash-course.stories.tsx`
+ - Copy: `__docs__/math-blaster-utils.ts` → `games/crash-course/crash-course-utils.ts`
+ - Copy: `__docs__/math-blaster-game.module.css` → `games/crash-course/crash-course.module.css`
+ - Copy: `__docs__/car-bonus-scene.tsx` → `games/crash-course/car-bonus-scene.tsx`
+ - Copy: `__docs__/car-bonus-scene.module.css` → `games/crash-course/car-bonus-scene.module.css`
+- **Acceptance criteria**:
+ - Files copied to new location
+ - Original files still work
+ - New location files have updated imports
+
+---
+
+### Task 11: Update Import Paths in Copied Files
+- **What**: Update asset import statements in the copied files
+- **Why**: Make copied files work with new asset locations
+- **Implementation notes**:
+ - Update image imports to use new asset paths
+ - Update audio imports to use new paths
+ - Update CSS imports
+ - Files should compile without errors
+- **Files affected**:
+ - Modified: `games/crash-course/crash-course.stories.tsx`
+ - Modified: `games/crash-course/car-bonus-scene.tsx`
+- **Acceptance criteria**:
+ - All imports resolve correctly
+ - No import errors when building
+ - TypeScript doesn't complain
+
+**Example import changes:**
+```typescript
+// Before (in __docs__)
+import run1Img from "./run1.png";
+import styles from "./math-blaster-game.module.css";
+
+// After (in games/crash-course/)
+import run1Img from "./assets/sprites/run1.png";
+import styles from "./crash-course.module.css";
+```
+
+---
+
+### Task 12: Update Storybook Story Metadata
+- **What**: Change Storybook title to "Games/Crash Course"
+- **Why**: Make it appear under "Games" section with correct name
+- **Implementation notes**:
+ - Update title in story metadata
+ - Update component name if needed
+ - Update description
+ - Keep as separate story from original (both exist temporarily)
+- **Files affected**:
+ - Modified: `games/crash-course/crash-course.stories.tsx`
+- **Acceptance criteria**:
+ - Story appears under "Games" in Storybook
+ - Title is "Crash Course" not "Math Blaster"
+ - Both old and new stories work
+
+**Example:**
+```typescript
+const meta: Meta = {
+ title: "Games/Crash Course",
+ component: CrashCourseGame,
+ parameters: {
+ docs: {
+ description: {
+ component: `
+# Crash Course
+
+An endless runner game showcasing Perseus widget integration.
+This is the refactored version with game engine architecture.
+
+**Location**: packages/perseus/src/games/crash-course/
+ `,
+ },
+ },
+ },
+};
+```
+
+---
+
+### Task 13: Create Asset Manifest
+- **What**: Create a manifest file listing all assets
+- **Why**: Centralized asset loading, easy to maintain
+- **Implementation notes**:
+ - List all images with keys
+ - List all audio with keys
+ - Export as TypeScript object
+ - Used by AssetLoader in Phase 2
+- **Files affected**:
+ - New: `games/crash-course/assets/asset-manifest.ts`
+- **Acceptance criteria**:
+ - All assets listed
+ - Correct paths
+ - Type-safe
+
+**Example:**
+```typescript
+// games/crash-course/assets/asset-manifest.ts
+
+import run1Img from "./sprites/run1.png";
+import run2Img from "./sprites/run2.png";
+// ... all other imports
+
+export const SPRITE_ASSETS = {
+ run1: run1Img,
+ run2: run2Img,
+ run3: run3Img,
+ run4: run4Img,
+ run5: run5Img,
+ run6: run6Img,
+ impact: impactImg,
+ idle: idleImg,
+ alien1: alien1Img,
+ alien2: alien2Img,
+ alien3: alien3Img,
+ car1: car1Img,
+ car2: car2Img,
+ beam: beamImg,
+} as const;
+
+export const BACKGROUND_ASSETS = {
+ sky: skyImg,
+ cityFar: cityFarImg,
+ citySemiFar: citySemiFarImg,
+ citySemiClose: citySemiCloseImg,
+ cityClose: cityCloseImg,
+ streetlamp: streetlampImg,
+ lamplight: lamplightImg,
+} as const;
+
+export const UI_ASSETS = {
+ title: titleImg,
+ start: startImg,
+ next: nextImg,
+ mute: muteImg,
+ unmute: unmuteImg,
+ victory: victoryImg,
+ lose: loseImg,
+ bonus1: bonus1Img,
+ bonus2: bonus2Img,
+ skid: skidImg,
+} as const;
+
+export const STORY_ASSETS = {
+ story1: story1Img,
+ story2: story2Img,
+ story3: story3Img,
+ story4: story4Img,
+ story5: story5Img,
+ story6: story6Img,
+ story7: story7Img,
+} as const;
+
+export const AUDIO_ASSETS = {
+ menuTheme: menuThemeAudio,
+ gameTheme1: gameTheme1Audio,
+ gameTheme2: gameTheme2Audio,
+ gameOverTheme: gameOverThemeAudio,
+} as const;
+
+export const ALL_ASSETS = {
+ sprites: SPRITE_ASSETS,
+ backgrounds: BACKGROUND_ASSETS,
+ ui: UI_ASSETS,
+ story: STORY_ASSETS,
+ audio: AUDIO_ASSETS,
+} as const;
+```
+
+---
+
+### Task 14: Verify Build and Type Checking
+- **What**: Ensure everything compiles and builds correctly
+- **Why**: Catch issues early before Phase 2
+- **Implementation notes**:
+ - Run `pnpm tsc` - should pass
+ - Run `pnpm lint` - should pass
+ - Run `pnpm build` - should succeed
+ - Original game still works in Storybook
+ - New (incomplete) game appears in Storybook
+- **Files affected**:
+ - N/A (verification task)
+- **Acceptance criteria**:
+ - TypeScript compilation passes
+ - Linting passes
+ - Build succeeds
+ - No import errors
+ - Original game works
+
+---
+
+### Task 15: Document Phase 1 Completion
+- **What**: Create a completion checklist and summary
+- **Why**: Verify everything is ready for Phase 2
+- **Implementation notes**:
+ - Check all directories created
+ - Check all assets moved
+ - Check types defined
+ - Check API documented
+ - Update main README
+- **Files affected**:
+ - New: `games/crash-course/PHASE_1_COMPLETE.md`
+- **Acceptance criteria**:
+ - All tasks completed
+ - Checklist verified
+ - Ready for Phase 2
+
+---
+
+## Deliverables
+
+After this phase, you should have:
+
+### Directory Structure ✅
+```
+games/
+├── crash-course/
+│ ├── assets/
+│ │ ├── sprites/ (14 files)
+│ │ ├── backgrounds/ (7 files)
+│ │ ├── ui/ (10 files)
+│ │ ├── audio/ (4 files)
+│ │ ├── story/ (7 files)
+│ │ └── asset-manifest.ts
+│ ├── engine/
+│ │ ├── CrashCourseEngine.ts (skeleton with API)
+│ │ ├── types.ts (complete types)
+│ │ ├── systems/ (empty, ready for Phase 2)
+│ │ └── utils/ (empty, ready for Phase 2)
+│ ├── components/ (empty, ready for Phase 3)
+│ ├── crash-course.stories.tsx (copied, imports updated)
+│ ├── crash-course-utils.ts (copied)
+│ ├── crash-course.module.css (copied)
+│ ├── car-bonus-scene.tsx (copied)
+│ ├── car-bonus-scene.module.css (copied)
+│ └── README.md
+└── shared/
+ └── perseus/
+ └── PerseusGameEngine.ts (interface definition)
+```
+
+### API Definitions ✅
+- GameState type
+- GameUIState type
+- Obstacle type
+- PerseusGameEngine interface
+- CrashCourseEngine public API (skeleton)
+
+### Assets Organized ✅
+- 42 assets moved to proper subdirectories
+- Asset manifest created
+- Git history preserved
+
+### Original Game Still Works ✅
+- Files remain in __docs__
+- Storybook story still functional
+- No breaking changes
+
+---
+
+## Testing Considerations
+
+After this phase:
+1. **Build Check**: `pnpm tsc` passes
+2. **Lint Check**: `pnpm lint` passes
+3. **Storybook Check**: Original game still works
+4. **Import Check**: New files compile without errors
+5. **Git Check**: History preserved with `git mv`
+
+---
+
+## Benefits After This Phase
+
+- ✅ **Clean organization** - Assets in logical folders
+- ✅ **Clear API contract** - Types and interfaces defined
+- ✅ **Ready for Phase 2** - Structure in place
+- ✅ **Reversible** - Original game still works
+- ✅ **Documented** - API fully specified with JSDoc
+
+---
+
+## Next Phase
+
+**Phase 2**: Build the game engine with all systems, implementing the API we designed in this phase.
+
+The foundation is set! 🏗️
diff --git a/packages/perseus/src/games/crash-course/plans/PHASE_2_build_engine.md b/packages/perseus/src/games/crash-course/plans/PHASE_2_build_engine.md
new file mode 100644
index 00000000000..24c1ab7f1ae
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PHASE_2_build_engine.md
@@ -0,0 +1,1048 @@
+# Phase 2: Build Game Engine
+
+**Part of**: [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+
+**Goal**: Extract all game logic into the CrashCourseEngine class with supporting systems, including a complete sprite animation system for managing multiple animated entities.
+
+**Estimated Effort**: 5-7 hours (most complex phase)
+
+## Overview
+
+This is the core refactoring work. We're moving all game loop logic, physics, collision detection, and canvas rendering from the React component into a pure TypeScript game engine. The engine will run independently at 60fps and communicate with React via callbacks.
+
+**Key Innovation**: Multi-entity sprite animation system built from the start, preventing future refactoring.
+
+## Tasks
+
+### Task 1: Create Engine Core Structure
+- **What**: Set up the basic CrashCourseEngine class with game loop
+- **Why**: Foundation for all game logic
+- **Implementation notes**:
+ - Create engine class with constructor, start(), stop(), pause()
+ - Implement requestAnimationFrame loop
+ - Track deltaTime between frames
+ - Set up canvas context
+ - Add callback for UI state updates (throttled to 10-15fps)
+- **Files affected**:
+ - New: `games/crash-course/engine/CrashCourseEngine.ts`
+ - New: `games/crash-course/engine/types.ts`
+- **Acceptance criteria**:
+ - Engine can start/stop
+ - Game loop runs at 60fps
+ - Can pass canvas reference
+ - Callback mechanism works
+
+**Example structure:**
+```typescript
+// games/crash-course/engine/CrashCourseEngine.ts
+
+type GameState = "start" | "story" | "playing" | "carBonus" | "gameover" | "victory";
+
+type GameUIState = {
+ gameState: GameState;
+ storyPage: number;
+ score: number;
+ lives: number;
+ gameTime: string;
+ currentQuestion: PerseusItem | null;
+};
+
+export class CrashCourseEngine {
+ private canvas: HTMLCanvasElement;
+ private ctx: CanvasRenderingContext2D;
+ private rafId: number | null = null;
+ private lastTime: number = 0;
+ private isRunning: boolean = false;
+
+ private gameState: GameState = "start";
+ private uiUpdateCallback: ((state: GameUIState) => void) | null = null;
+ private frameCount: number = 0;
+
+ constructor(canvas: HTMLCanvasElement, onUIUpdate: (state: GameUIState) => void) {
+ this.canvas = canvas;
+ this.ctx = canvas.getContext('2d')!;
+ this.uiUpdateCallback = onUIUpdate;
+ }
+
+ start(): void {
+ this.isRunning = true;
+ this.lastTime = performance.now();
+ this.loop(this.lastTime);
+ }
+
+ stop(): void {
+ this.isRunning = false;
+ if (this.rafId !== null) {
+ cancelAnimationFrame(this.rafId);
+ this.rafId = null;
+ }
+ }
+
+ pause(): void {
+ this.isRunning = false;
+ }
+
+ resume(): void {
+ if (!this.isRunning) {
+ this.isRunning = true;
+ this.lastTime = performance.now();
+ this.loop(this.lastTime);
+ }
+ }
+
+ private loop = (currentTime: number): void => {
+ if (!this.isRunning) return;
+
+ const deltaTime = currentTime - this.lastTime;
+ this.lastTime = currentTime;
+
+ // Update game logic
+ this.update(deltaTime);
+
+ // Render game
+ this.render();
+
+ // Notify React of UI state changes (throttled to 10fps)
+ this.frameCount++;
+ if (this.frameCount % 6 === 0) {
+ this.notifyUIUpdate();
+ }
+
+ // Continue loop
+ this.rafId = requestAnimationFrame(this.loop);
+ };
+
+ private update(deltaTime: number): void {
+ // Game logic goes here
+ // Will be filled in subsequent tasks
+ }
+
+ private render(): void {
+ // Canvas rendering goes here
+ // Will be filled in subsequent tasks
+ }
+
+ private notifyUIUpdate(): void {
+ if (this.uiUpdateCallback) {
+ this.uiUpdateCallback(this.getUIState());
+ }
+ }
+
+ private getUIState(): GameUIState {
+ return {
+ gameState: this.gameState,
+ storyPage: this.storyPage,
+ score: this.score,
+ lives: this.lives,
+ gameTime: this.formatGameTime(),
+ currentQuestion: this.getCurrentQuestion(),
+ };
+ }
+
+ // Public API for React to call
+ getCurrentState(): GameState {
+ return this.gameState;
+ }
+
+ startStory(): void {
+ this.gameState = "story";
+ this.storyPage = 1;
+ }
+
+ nextStoryPage(): void {
+ if (this.storyPage < 7) {
+ this.storyPage++;
+ } else {
+ this.startPlaying();
+ }
+ }
+
+ startPlaying(): void {
+ this.gameState = "playing";
+ this.gameStartTime = Date.now();
+ // Initialize game state
+ }
+}
+```
+
+---
+
+### Task 2: Build SpriteAnimator System
+- **What**: Create low-level animation controller for frame sequencing
+- **Why**: Foundation for all sprite animation, reusable across games
+- **Implementation notes**:
+ - Support individual frame images
+ - Support spritesheets (grid of frames)
+ - Named animation sequences
+ - FPS control, looping, callbacks
+ - Visual effects (tint, flip, alpha)
+ - Frame timing with deltaTime
+- **Files affected**:
+ - New: `games/crash-course/engine/systems/SpriteAnimator.ts`
+- **Acceptance criteria**:
+ - Can load individual frames or spritesheet
+ - Can define named animations
+ - Play/stop/pause animations
+ - Update with deltaTime
+ - Returns current frame image
+ - Effects work (tint, flip)
+
+**See full implementation in previous message - the complete SpriteAnimator class**
+
+---
+
+### Task 3: Build AnimatedSprite Class
+- **What**: High-level sprite entity combining position, size, and animation
+- **Why**: Makes working with sprites easier, handles position + drawing
+- **Implementation notes**:
+ - Wraps SpriteAnimator
+ - Tracks x, y, width, height
+ - Has layer property for z-ordering
+ - Convenience methods (play, update, draw)
+ - Returns bounding box for collision
+- **Files affected**:
+ - New: `games/crash-course/engine/systems/AnimatedSprite.ts`
+- **Acceptance criteria**:
+ - Combines animator with position
+ - Can update and draw itself
+ - Layer system works
+ - Bounding box for collision
+
+**See full implementation in previous message - the complete AnimatedSprite class**
+
+---
+
+### Task 4: Build SpriteManager System
+- **What**: Manages all animated sprites in the game with batch operations
+- **Why**: Central registry for all sprites, batch update/draw, layer management
+- **Implementation notes**:
+ - Create sprites with config
+ - Register sprites by ID
+ - Get sprites by ID or layer
+ - Batch update all sprites
+ - Batch draw with layer ordering
+ - Dynamic sprite creation/removal (for obstacles)
+- **Files affected**:
+ - New: `games/crash-course/engine/systems/SpriteManager.ts`
+- **Acceptance criteria**:
+ - Can create sprites from config
+ - Can retrieve sprites by ID
+ - updateAll() updates all sprites
+ - drawByLayers() draws in order
+ - Can add/remove sprites dynamically
+ - Layer system works
+
+**See full implementation in previous message - the complete SpriteManager class**
+
+---
+
+### Task 5: Build RenderSystem
+- **What**: Canvas drawing utilities and helpers
+- **Why**: Reusable drawing operations, separate from game logic
+- **Implementation notes**:
+ - Basic drawing primitives (rectangle, circle, text)
+ - Parallax background helpers
+ - Text rendering with styles
+ - Utility functions for common operations
+- **Files affected**:
+ - New: `games/crash-course/engine/systems/RenderSystem.ts`
+- **Acceptance criteria**:
+ - Helper functions for drawing
+ - Clean API
+ - Reusable across games
+
+**Example:**
+```typescript
+// games/crash-course/engine/systems/RenderSystem.ts
+
+export class RenderSystem {
+ constructor(private ctx: CanvasRenderingContext2D) {}
+
+ clear(): void {
+ const canvas = this.ctx.canvas;
+ this.ctx.clearRect(0, 0, canvas.width, canvas.height);
+ }
+
+ drawRect(
+ x: number,
+ y: number,
+ width: number,
+ height: number,
+ color: string
+ ): void {
+ this.ctx.fillStyle = color;
+ this.ctx.fillRect(x, y, width, height);
+ }
+
+ drawText(
+ text: string,
+ x: number,
+ y: number,
+ style: {
+ font?: string;
+ color?: string;
+ align?: CanvasTextAlign;
+ baseline?: CanvasTextBaseline;
+ } = {}
+ ): void {
+ this.ctx.save();
+
+ if (style.font) this.ctx.font = style.font;
+ if (style.color) this.ctx.fillStyle = style.color;
+ if (style.align) this.ctx.textAlign = style.align;
+ if (style.baseline) this.ctx.textBaseline = style.baseline;
+
+ this.ctx.fillText(text, x, y);
+
+ this.ctx.restore();
+ }
+
+ drawParallaxLayer(
+ image: HTMLImageElement,
+ offset: number,
+ y: number,
+ height: number
+ ): void {
+ const canvas = this.ctx.canvas;
+ const width = canvas.width;
+
+ // Draw two copies for seamless looping
+ this.ctx.drawImage(image, -offset, y, width, height);
+ this.ctx.drawImage(image, width - offset, y, width, height);
+ }
+}
+```
+
+---
+
+### Task 6: Build AudioSystem
+- **What**: Audio management with multiple tracks and volume control
+- **Why**: Reusable audio handling, clean API
+- **Implementation notes**:
+ - Load and manage multiple audio tracks
+ - Play/stop/pause functionality
+ - Volume control and muting
+ - Fade in/out
+ - Track transitions (tedox → neon owl)
+- **Files affected**:
+ - New: `games/crash-course/engine/systems/AudioSystem.ts`
+- **Acceptance criteria**:
+ - Can load multiple tracks
+ - Play/stop/pause works
+ - Volume and mute work
+ - Fade transitions work
+ - Handles autoplay restrictions
+
+**Example:**
+```typescript
+// games/crash-course/engine/systems/AudioSystem.ts
+
+export class AudioSystem {
+ private tracks = new Map();
+ private currentTrack: string | null = null;
+ private isMuted: boolean = false;
+ private volume: number = 0.5;
+
+ async loadTrack(name: string, url: string, loop: boolean = false): Promise {
+ const audio = new Audio(url);
+ audio.loop = loop;
+ audio.volume = this.volume;
+ this.tracks.set(name, audio);
+ }
+
+ play(trackName: string): void {
+ const track = this.tracks.get(trackName);
+ if (!track) {
+ console.warn(`Track "${trackName}" not found`);
+ return;
+ }
+
+ // Stop current track if different
+ if (this.currentTrack && this.currentTrack !== trackName) {
+ this.stop(this.currentTrack);
+ }
+
+ this.currentTrack = trackName;
+
+ if (!this.isMuted) {
+ track.currentTime = 0;
+ track.play().catch((error) => {
+ console.log(`Audio play failed: ${error}`);
+ });
+ }
+ }
+
+ stop(trackName: string): void {
+ const track = this.tracks.get(trackName);
+ if (track) {
+ track.pause();
+ track.currentTime = 0;
+ }
+ }
+
+ stopAll(): void {
+ for (const track of this.tracks.values()) {
+ track.pause();
+ track.currentTime = 0;
+ }
+ this.currentTrack = null;
+ }
+
+ setVolume(volume: number): void {
+ this.volume = Math.max(0, Math.min(1, volume));
+ for (const track of this.tracks.values()) {
+ track.volume = this.volume;
+ }
+ }
+
+ mute(): void {
+ this.isMuted = true;
+ for (const track of this.tracks.values()) {
+ track.pause();
+ }
+ }
+
+ unmute(): void {
+ this.isMuted = false;
+ if (this.currentTrack) {
+ this.play(this.currentTrack);
+ }
+ }
+
+ fadeOut(trackName: string, duration: number): void {
+ const track = this.tracks.get(trackName);
+ if (!track) return;
+
+ const startVolume = track.volume;
+ const startTime = Date.now();
+
+ const fade = () => {
+ const elapsed = Date.now() - startTime;
+ const progress = Math.min(elapsed / duration, 1);
+
+ track.volume = startVolume * (1 - progress);
+
+ if (progress < 1) {
+ requestAnimationFrame(fade);
+ } else {
+ this.stop(trackName);
+ track.volume = startVolume; // Reset volume
+ }
+ };
+
+ fade();
+ }
+}
+```
+
+---
+
+### Task 7: Build AssetLoader System
+- **What**: Load and manage all game assets (images, audio)
+- **Why**: Centralized asset loading with progress tracking and error handling
+- **Implementation notes**:
+ - Load images with progress tracking
+ - Load audio files
+ - Error handling and retries
+ - Progress callbacks for loading screen
+ - Return loaded assets as Map
+- **Files affected**:
+ - New: `games/crash-course/engine/systems/AssetLoader.ts`
+- **Acceptance criteria**:
+ - Can load multiple images
+ - Can load multiple audio files
+ - Progress tracking works
+ - Error handling works
+ - Returns organized assets
+
+**Example:**
+```typescript
+// games/crash-course/engine/systems/AssetLoader.ts
+
+type AssetManifest = {
+ images: {[key: string]: string};
+ audio: {[key: string]: string};
+};
+
+export class AssetLoader {
+ private images = new Map();
+ private audio = new Map();
+
+ async loadAll(
+ manifest: AssetManifest,
+ onProgress?: (progress: number) => void
+ ): Promise {
+ const imageEntries = Object.entries(manifest.images);
+ const audioEntries = Object.entries(manifest.audio);
+ const total = imageEntries.length + audioEntries.length;
+ let loaded = 0;
+
+ const updateProgress = () => {
+ loaded++;
+ if (onProgress) {
+ onProgress(loaded / total);
+ }
+ };
+
+ // Load images
+ const imagePromises = imageEntries.map(([key, url]) =>
+ this.loadImage(url).then((img) => {
+ this.images.set(key, img);
+ updateProgress();
+ })
+ );
+
+ // Load audio
+ const audioPromises = audioEntries.map(([key, url]) =>
+ this.loadAudio(url).then((audio) => {
+ this.audio.set(key, audio);
+ updateProgress();
+ })
+ );
+
+ await Promise.all([...imagePromises, ...audioPromises]);
+ }
+
+ getImage(key: string): HTMLImageElement | undefined {
+ return this.images.get(key);
+ }
+
+ getAudio(key: string): HTMLAudioElement | undefined {
+ return this.audio.get(key);
+ }
+
+ private loadImage(url: string): Promise {
+ return new Promise((resolve, reject) => {
+ const img = new Image();
+ img.onload = () => resolve(img);
+ img.onerror = () => reject(new Error(`Failed to load image: ${url}`));
+ img.src = url;
+ });
+ }
+
+ private loadAudio(url: string): Promise {
+ return new Promise((resolve, reject) => {
+ const audio = new Audio();
+ audio.oncanplaythrough = () => resolve(audio);
+ audio.onerror = () => reject(new Error(`Failed to load audio: ${url}`));
+ audio.src = url;
+ });
+ }
+}
+```
+
+---
+
+### Task 8: Implement Perseus Integration Interface
+- **What**: Define and implement the Perseus question integration interface
+- **Why**: Standard pattern for educational games, reusable across games
+- **Implementation notes**:
+ - Create PerseusGameEngine interface
+ - Implement in CrashCourseEngine
+ - getCurrentQuestion() for React to render
+ - submitAnswer() for React to call with result
+ - onQuestionChange callback for updates
+- **Files affected**:
+ - New: `games/shared/perseus/PerseusGameEngine.ts` (create shared directory!)
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Interface defined and documented
+ - CrashCourseEngine implements interface
+ - React can get current question
+ - React can submit answers
+ - Callback system works
+
+**Example:**
+```typescript
+// games/shared/perseus/PerseusGameEngine.ts
+
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Interface that all educational games must implement for Perseus integration.
+ *
+ * Provides a consistent way for games to integrate Perseus questions,
+ * regardless of game mechanics.
+ */
+export interface PerseusGameEngine {
+ /**
+ * Get the current question to display to the player.
+ * Returns null if no question is active.
+ */
+ getCurrentQuestion(): PerseusItem | null;
+
+ /**
+ * Called when the player submits an answer.
+ *
+ * @param correct - Whether the answer was correct
+ * @param earnedPoints - Points earned (from Perseus scoring)
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void;
+
+ /**
+ * Register callback for question state changes.
+ * Allows React to re-render when questions change.
+ */
+ onQuestionChange(callback: (question: PerseusItem | null) => void): void;
+}
+
+// CrashCourseEngine implements this
+export class CrashCourseEngine implements PerseusGameEngine {
+ private currentObstacle: Obstacle | null = null;
+ private questionCallback: ((q: PerseusItem | null) => void) | null = null;
+
+ getCurrentQuestion(): PerseusItem | null {
+ return this.currentObstacle?.question ?? null;
+ }
+
+ submitAnswer(correct: boolean, earnedPoints: number): void {
+ if (!this.currentObstacle) return;
+
+ this.currentObstacle.answered = true;
+ this.currentObstacle.correct = correct;
+
+ if (correct) {
+ this.score += earnedPoints;
+ this.enterCoolMode();
+ this.currentObstacle.jumped = true; // Trigger jump
+ }
+
+ this.currentObstacle = null;
+ this.questionCallback?.(null);
+ }
+
+ onQuestionChange(callback: (q: PerseusItem | null) => void): void {
+ this.questionCallback = callback;
+ }
+}
+```
+
+---
+
+### Task 9: Move Game State Machine to Engine
+- **What**: Implement game state management in engine
+- **Why**: Engine controls flow, React just displays current state
+- **Implementation notes**:
+ - State: start, story, playing, carBonus, gameover, victory
+ - Story page tracking (1-7)
+ - Timer for victory condition (5 minutes)
+ - Public methods for state transitions
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - State machine works correctly
+ - Story pages advance
+ - Timer triggers victory
+ - React can query current state
+
+---
+
+### Task 10: Move Physics and Collision to Engine
+- **What**: Implement jump physics, obstacle movement, collision detection
+- **Why**: Core game mechanics, needs to run at 60fps
+- **Implementation notes**:
+ - Jump physics (parabolic arc)
+ - Obstacle movement (scrolling + racing away)
+ - Collision detection (rectangle collision)
+ - Life system
+ - Alien abduction rescue mechanic
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+ - New: `games/crash-course/engine/utils/physics.ts`
+ - New: `games/crash-course/engine/utils/collision.ts`
+- **Acceptance criteria**:
+ - Jump feels right (same as original)
+ - Obstacles move correctly
+ - Collision detection works
+ - Life loss works
+ - Alien rescue works
+
+**Example physics utilities:**
+```typescript
+// games/crash-course/engine/utils/physics.ts
+
+export function calculateJumpY(
+ startTime: number,
+ currentTime: number,
+ groundY: number,
+ jumpHeight: number,
+ jumpDuration: number
+): {y: number; isComplete: boolean} {
+ const elapsed = currentTime - startTime;
+
+ if (elapsed >= jumpDuration) {
+ return {y: groundY, isComplete: true};
+ }
+
+ const progress = elapsed / jumpDuration;
+ const height = Math.sin(progress * Math.PI) * jumpHeight;
+
+ return {y: groundY - height, isComplete: false};
+}
+
+// games/crash-course/engine/utils/collision.ts
+
+export function checkRectCollision(
+ x1: number, y1: number, w1: number, h1: number,
+ x2: number, y2: number, w2: number, h2: number
+): boolean {
+ return x1 < x2 + w2 && x1 + w1 > x2 &&
+ y1 < y2 + h2 && y1 + h1 > y2;
+}
+```
+
+---
+
+### Task 11: Migrate Character to Sprite System
+- **What**: Create character sprite using SpriteManager
+- **Why**: Test sprite system, clean up character rendering
+- **Implementation notes**:
+ - Load character frames
+ - Define run, impact animations
+ - Cool mode uses tint effect
+ - Update position from physics
+ - Remove old character rendering code
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Character renders via sprite system
+ - Animations work (run, impact, cool mode)
+ - Cool mode tint works
+ - Position updates correctly
+
+---
+
+### Task 12: Migrate Alien to Sprite System
+- **What**: Create alien sprite with blinking animation
+- **Why**: Test sprite system with callbacks
+- **Implementation notes**:
+ - Load alien frames (3 frames)
+ - Define idle, blink animations
+ - Blink triggers periodically
+ - Floating motion updates position
+ - Abduction mode changes position
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Alien renders via sprite system
+ - Blinking works
+ - Floating motion works
+ - Abduction positioning works
+
+---
+
+### Task 13: Migrate Obstacles to Sprite System
+- **What**: Create car sprites dynamically as obstacles spawn
+- **Why**: Test dynamic sprite creation/removal
+- **Implementation notes**:
+ - When obstacle spawns, create sprite
+ - When obstacle leaves screen, remove sprite
+ - Car animation plays
+ - Collision uses sprite bounds
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Cars render via sprite system
+ - Sprites created/destroyed correctly
+ - Collision works with sprites
+ - No memory leaks (sprites properly removed)
+
+---
+
+### Task 14: Move Parallax Background to Engine
+- **What**: Implement parallax scrolling background
+- **Why**: Visual effect, part of game rendering
+- **Implementation notes**:
+ - 5 layers (sky, cityFar, citySemiFar, citySemiClose, cityClose)
+ - Different scroll speeds
+ - Seamless looping
+ - Use RenderSystem helpers
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Parallax scrolling works
+ - Seamless looping
+ - Performance good (60fps)
+
+---
+
+### Task 15: Move Obstacle Spawning to Engine
+- **What**: Spawn obstacles at intervals with Perseus questions
+- **Why**: Core game mechanic
+- **Implementation notes**:
+ - Spawn every 5 seconds
+ - Create Perseus question (from crash-course-utils)
+ - Create car sprite
+ - Track obstacles array
+ - Set as current question when close
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+ - Keep: `games/crash-course/crash-course-utils.ts` (question generation)
+- **Acceptance criteria**:
+ - Obstacles spawn correctly
+ - Perseus questions attached
+ - Current question updates
+ - React receives question updates
+
+---
+
+### Task 16: Integrate Audio with Game States
+- **What**: Wire up AudioSystem to play correct music per game state
+- **Why**: Audio is part of game experience
+- **Implementation notes**:
+ - Menu music on start screen
+ - Game music during story/playing
+ - Tedox → Neon Owl transition
+ - Game over music
+ - Mute functionality
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Correct music plays per state
+ - Transitions work
+ - Mute works
+ - No audio errors
+
+---
+
+### Task 17: Implement Timer and Victory Condition
+- **What**: Track game time and trigger victory at 5 minutes
+- **Why**: Win condition for the game
+- **Implementation notes**:
+ - Track elapsed time from game start
+ - Format as game time (11:55:00 → 00:00:00)
+ - Trigger victory at 5 minutes
+ - Update UI state with formatted time
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - Timer counts up correctly
+ - Time displays correctly
+ - Victory triggers at 5 minutes
+ - React receives time updates
+
+---
+
+### Task 18: Test Engine Independently
+- **What**: Write unit tests for engine logic
+- **Why**: Verify engine works without React
+- **Implementation notes**:
+ - Test obstacle spawning
+ - Test collision detection
+ - Test state transitions
+ - Test Perseus integration
+ - Test physics calculations
+ - Mock canvas context
+- **Files affected**:
+ - New: `games/crash-course/engine/CrashCourseEngine.test.ts`
+- **Acceptance criteria**:
+ - Engine can run headless
+ - Unit tests pass
+ - Core mechanics tested
+ - No React dependencies in tests
+
+**Example test:**
+```typescript
+describe("CrashCourseEngine", () => {
+ let mockCanvas: HTMLCanvasElement;
+ let engine: CrashCourseEngine;
+ let uiUpdates: GameUIState[] = [];
+
+ beforeEach(() => {
+ mockCanvas = document.createElement('canvas');
+ engine = new CrashCourseEngine(mockCanvas, (state) => {
+ uiUpdates.push(state);
+ });
+ });
+
+ it("starts in 'start' state", () => {
+ expect(engine.getCurrentState()).toBe("start");
+ });
+
+ it("transitions through story pages", () => {
+ engine.startStory();
+ expect(engine.getCurrentState()).toBe("story");
+
+ for (let i = 0; i < 7; i++) {
+ engine.nextStoryPage();
+ }
+
+ expect(engine.getCurrentState()).toBe("playing");
+ });
+
+ it("spawns obstacles with Perseus questions", () => {
+ engine.startPlaying();
+
+ // Simulate 5 seconds
+ jest.advanceTimersByTime(5000);
+
+ const question = engine.getCurrentQuestion();
+ expect(question).not.toBeNull();
+ expect(question).toHaveProperty('question');
+ });
+
+ it("handles correct answer", () => {
+ engine.startPlaying();
+ jest.advanceTimersByTime(5000);
+
+ const initialScore = engine.getScore();
+ engine.submitAnswer(true, 10);
+
+ expect(engine.getScore()).toBe(initialScore + 10);
+ });
+});
+```
+
+---
+
+### Task 19: Create Engine Constants File
+- **What**: Extract all magic numbers to constants
+- **Why**: Centralized configuration, easier to tune
+- **Implementation notes**:
+ - Canvas dimensions
+ - Physics constants (gravity, jump height, speed)
+ - Game config (duration, spawn interval)
+ - Sprite sizes
+- **Files affected**:
+ - New: `games/crash-course/engine/constants.ts`
+- **Acceptance criteria**:
+ - All magic numbers extracted
+ - Well-organized by category
+ - Documented with comments
+
+**Example:**
+```typescript
+// games/crash-course/engine/constants.ts
+
+export const CANVAS = {
+ WIDTH: 800,
+ HEIGHT: 600,
+} as const;
+
+export const PHYSICS = {
+ GROUND_Y: 450,
+ SCROLL_SPEED: 2,
+ JUMP_HEIGHT: 140,
+ JUMP_DURATION: 1000, // milliseconds
+ GRAVITY: 0.5,
+} as const;
+
+export const GAME_CONFIG = {
+ DURATION: 300000, // 5 minutes
+ OBSTACLE_SPAWN_INTERVAL: 5000, // 5 seconds
+ COOL_MODE_DURATION: 2000, // 2 seconds
+ LAMP_SPACING: 500, // pixels
+} as const;
+
+export const SPRITE_SIZES = {
+ CHARACTER: 128,
+ ALIEN: 96,
+ CAR: 154,
+} as const;
+
+export const CHARACTER = {
+ X: 100,
+ WIDTH: SPRITE_SIZES.CHARACTER,
+ HEIGHT: SPRITE_SIZES.CHARACTER,
+ COLLISION_ZONE_X: 120,
+} as const;
+```
+
+---
+
+### Task 20: Document Engine API
+- **What**: Add JSDoc comments to public engine methods
+- **Why**: Clear API for React component to use
+- **Implementation notes**:
+ - Document constructor
+ - Document public methods (start, stop, startStory, etc.)
+ - Document callbacks
+ - Add usage examples
+- **Files affected**:
+ - Modified: `games/crash-course/engine/CrashCourseEngine.ts`
+- **Acceptance criteria**:
+ - All public methods documented
+ - Examples included
+ - Clear parameter descriptions
+
+---
+
+## Directory Structure After This Phase
+
+```
+games/crash-course/
+├── engine/
+│ ├── CrashCourseEngine.ts (Main engine class)
+│ ├── CrashCourseEngine.test.ts (Engine tests)
+│ ├── types.ts (Engine-specific types)
+│ ├── constants.ts (Game constants)
+│ ├── systems/
+│ │ ├── SpriteAnimator.ts (Animation controller)
+│ │ ├── AnimatedSprite.ts (Sprite entity)
+│ │ ├── SpriteManager.ts (Multi-sprite management)
+│ │ ├── RenderSystem.ts (Canvas utilities)
+│ │ ├── AudioSystem.ts (Audio management)
+│ │ └── AssetLoader.ts (Asset loading)
+│ └── utils/
+│ ├── physics.ts (Physics calculations)
+│ └── collision.ts (Collision detection)
+├── assets/ (From Phase 1)
+│ ├── sprites/
+│ ├── backgrounds/
+│ ├── ui/
+│ ├── audio/
+│ └── story/
+├── crash-course-utils.ts (Question generation - keep as is)
+└── crash-course.stories.tsx (Will update in Phase 3)
+
+games/shared/ (NEW - shared across games)
+└── perseus/
+ └── PerseusGameEngine.ts (Interface for Perseus integration)
+```
+
+---
+
+## Testing Considerations
+
+After this phase:
+1. **Engine Tests**: Unit tests pass, engine runs headless
+2. **Performance**: Measure FPS (should be 60fps stable)
+3. **Memory**: Check for leaks (sprites properly cleaned up)
+4. **Sprite System**: All entities render correctly
+5. **Perseus Integration**: Questions appear and can be answered
+
+### How to Test Without React:
+
+```typescript
+// Test engine in isolation
+const canvas = document.createElement('canvas');
+const engine = new CrashCourseEngine(canvas, (state) => {
+ console.log("UI State:", state);
+});
+
+await engine.init();
+engine.start();
+
+// Engine runs independently!
+// Should see console logs of UI state updates
+```
+
+---
+
+## Benefits After This Phase
+
+- ✅ **Game logic separate from React** - Clean architecture
+- ✅ **60fps game loop** - Not affected by React rendering
+- ✅ **Multi-entity sprite system** - Supports any number of animated sprites
+- ✅ **Testable** - Can unit test engine without React
+- ✅ **Reusable systems** - Sprite, audio, render systems ready to extract
+- ✅ **Perseus integration** - Standard interface for educational games
+- ✅ **Clear API** - React knows exactly how to communicate with engine
+
+---
+
+## Next Phase
+
+**Phase 3**: Create thin React wrapper and UI components that connect to the engine via callbacks.
+
+The hard work is done - React becomes simple after this! 🚀
diff --git a/packages/perseus/src/games/crash-course/plans/PHASE_3_ui_components.md b/packages/perseus/src/games/crash-course/plans/PHASE_3_ui_components.md
new file mode 100644
index 00000000000..d5542f53be0
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PHASE_3_ui_components.md
@@ -0,0 +1,800 @@
+# Phase 3: Extract UI Components & Wire Up
+
+**Part of**: [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+
+**Goal**: Create React components for UI overlays and connect them to the game engine.
+
+**Estimated Effort**: 2-3 hours
+
+## Overview
+
+Now that the engine is working, we build the React wrapper. This phase is much simpler than the original plan because the engine handles all game logic. React becomes a thin UI layer that:
+- Renders canvas for the engine
+- Shows UI overlays (screens, HUD, questions)
+- Calls engine methods in response to user actions
+
+The engine runs at 60fps, React updates at 10-15fps when UI state changes.
+
+## Tasks
+
+### Task 1: Create Main Component Wrapper
+- **What**: Build the main CrashCourseGame component that wraps the engine
+- **Why**: Connects React to the engine
+- **Implementation notes**:
+ - Create ref for canvas element
+ - Create engine instance in useEffect
+ - Initialize engine and start it
+ - Listen for UI state updates
+ - Clean up on unmount
+ - Render canvas + UI overlays based on state
+- **Files affected**:
+ - New: `games/crash-course/CrashCourseGame.tsx` (replaces .stories.tsx main component)
+ - Modified: `games/crash-course/crash-course.stories.tsx` (just exports the component now)
+- **Acceptance criteria**:
+ - Engine initializes and starts
+ - Canvas renders
+ - UI state updates trigger re-renders
+ - Engine stops on unmount
+ - No memory leaks
+
+**Example structure:**
+```typescript
+// games/crash-course/CrashCourseGame.tsx
+
+import * as React from "react";
+import {useEffect, useRef, useState} from "react";
+import {View} from "@khanacademy/wonder-blocks-core";
+
+import {CrashCourseEngine} from "./engine/CrashCourseEngine";
+import type {GameUIState} from "./engine/types";
+import styles from "./crash-course.module.css";
+
+// UI components (will create in subsequent tasks)
+import {StartScreen} from "./components/StartScreen";
+import {StoryScreen} from "./components/StoryScreen";
+import {HUD} from "./components/HUD";
+import {QuestionOverlay} from "./components/QuestionOverlay";
+import {VictoryScreen} from "./components/VictoryScreen";
+import {GameOverScreen} from "./components/GameOverScreen";
+import {MuteButton} from "./components/MuteButton";
+import {BenevolenceMessage} from "./components/BenevolenceMessage";
+import {CarBonusScene} from "./car-bonus-scene";
+
+/**
+ * Crash Course - An endless runner educational game.
+ *
+ * Integrates Perseus widgets with game mechanics.
+ * Players answer math questions to jump over obstacles.
+ */
+export const CrashCourseGame = (): React.ReactElement => {
+ const canvasRef = useRef(null);
+ const engineRef = useRef(null);
+
+ const [uiState, setUIState] = useState(null);
+ const [isMuted, setIsMuted] = useState(false);
+ const [isLoading, setIsLoading] = useState(true);
+
+ // Initialize engine
+ useEffect(() => {
+ if (!canvasRef.current) return;
+
+ const engine = new CrashCourseEngine({
+ canvas: canvasRef.current,
+ onUIUpdate: setUIState,
+ muted: isMuted,
+ });
+
+ engineRef.current = engine;
+
+ // Initialize and start engine
+ engine.init().then(() => {
+ setIsLoading(false);
+ engine.start();
+ });
+
+ // Cleanup
+ return () => {
+ engine.stop();
+ engineRef.current = null;
+ };
+ }, []);
+
+ // Handle mute toggle
+ const handleToggleMute = () => {
+ setIsMuted(!isMuted);
+ engineRef.current?.toggleMute();
+ };
+
+ // Handle answer submission from QuestionOverlay
+ const handleCheckAnswer = (correct: boolean, points: number) => {
+ engineRef.current?.submitAnswer(correct, points);
+ };
+
+ if (isLoading) {
+ return Loading...
;
+ }
+
+ if (!uiState) {
+ return Initializing...
;
+ }
+
+ return (
+
+
+ {/* Canvas - engine draws here */}
+
+
+ {/* Mute button - always visible */}
+
+
+ {/* Start screen */}
+ {uiState.gameState === "start" && (
+ engineRef.current?.startStory()}
+ />
+ )}
+
+ {/* Story screen */}
+ {uiState.gameState === "story" && (
+ engineRef.current?.nextStoryPage()}
+ />
+ )}
+
+ {/* Playing state - HUD and question */}
+ {uiState.gameState === "playing" && (
+ <>
+
+
+ {uiState.currentQuestion && (
+
+ )}
+
+ {uiState.showBenevolence && }
+
+ )}
+
+ {/* Car bonus scene */}
+ {uiState.gameState === "carBonus" && (
+ {
+ // Engine will transition to gameover
+ }}
+ />
+ )}
+
+ {/* Victory screen */}
+ {uiState.gameState === "victory" && (
+ engineRef.current?.startStory()}
+ />
+ )}
+
+ {/* Game over screen */}
+ {uiState.gameState === "gameover" && (
+ engineRef.current?.startStory()}
+ />
+ )}
+
+
+ );
+};
+```
+
+---
+
+### Task 2: Create StartScreen Component
+- **What**: Title screen with start button
+- **Why**: Clean separation of UI concerns
+- **Implementation notes**:
+ - Display title image
+ - Show start button
+ - Handle click to start
+ - Use existing CSS styles
+- **Files affected**:
+ - New: `games/crash-course/components/StartScreen.tsx`
+- **Acceptance criteria**:
+ - Renders title correctly
+ - Start button triggers callback
+ - Styling preserved
+
+**Example:**
+```typescript
+// games/crash-course/components/StartScreen.tsx
+
+import * as React from "react";
+import titleImg from "../assets/ui/title.png";
+import startImg from "../assets/ui/start.png";
+import styles from "../crash-course.module.css";
+
+type StartScreenProps = {
+ onStart: () => void;
+};
+
+export const StartScreen = ({onStart}: StartScreenProps): React.ReactElement => {
+ return (
+
+
+
+
+
+
+
+
{gameTime}
+
+
Score: {score}
+
+
+ Alien Benevolence:
+ 0 ? styles.alien : `${styles.alien} ${styles.alienLost}`}>
+ 👽
+
+ 1 ? styles.alien : `${styles.alien} ${styles.alienLost}`}>
+ 👽
+
+ 2 ? styles.alien : `${styles.alien} ${styles.alienLost}`}>
+ 👽
+
+
+
+
+
+
+
+ {feedback.show && (
+
+ {feedback.message}
+
+ )}
+
+ );
+};
+```
+
+---
+
+### Task 9: Create BenevolenceMessage Component
+- **What**: "BENEVOLENCE" message animation
+- **Why**: Shows when alien saves player
+- **Implementation notes**:
+ - Display text with animation
+ - Auto-hide after 2 seconds
+ - Use CSS animation
+- **Files affected**:
+ - New: `games/crash-course/components/BenevolenceMessage.tsx`
+- **Acceptance criteria**:
+ - Message displays
+ - Animation plays
+ - Auto-hides
+
+**Example:**
+```typescript
+// games/crash-course/components/BenevolenceMessage.tsx
+
+import * as React from "react";
+import styles from "../crash-course.module.css";
+
+export const BenevolenceMessage = (): React.ReactElement => {
+ return BENEVOLENCE
;
+};
+```
+
+---
+
+### Task 10: Create Components Index
+- **What**: Barrel export for all components
+- **Why**: Clean imports in main component
+- **Implementation notes**:
+ - Export all components from index.ts
+ - Simplifies imports
+- **Files affected**:
+ - New: `games/crash-course/components/index.ts`
+- **Acceptance criteria**:
+ - All components exported
+ - Can import from components/
+
+**Example:**
+```typescript
+// games/crash-course/components/index.ts
+
+export {StartScreen} from "./StartScreen";
+export {StoryScreen} from "./StoryScreen";
+export {HUD} from "./HUD";
+export {QuestionOverlay} from "./QuestionOverlay";
+export {VictoryScreen} from "./VictoryScreen";
+export {GameOverScreen} from "./GameOverScreen";
+export {MuteButton} from "./MuteButton";
+export {BenevolenceMessage} from "./BenevolenceMessage";
+```
+
+---
+
+### Task 11: Update Storybook Story
+- **What**: Update story file to use new component
+- **Why**: Keep Storybook working
+- **Implementation notes**:
+ - Import CrashCourseGame component
+ - Export as default story
+ - Update metadata if needed
+- **Files affected**:
+ - Modified: `games/crash-course/crash-course.stories.tsx`
+- **Acceptance criteria**:
+ - Story exports component
+ - Works in Storybook
+ - Title is "Games/Crash Course"
+
+**Example:**
+```typescript
+// games/crash-course/crash-course.stories.tsx
+
+import type {Meta, StoryObj} from "@storybook/react-vite";
+import {CrashCourseGame} from "./CrashCourseGame";
+
+const meta: Meta = {
+ title: "Games/Crash Course",
+ component: CrashCourseGame,
+ parameters: {
+ docs: {
+ description: {
+ component: "Educational endless runner with Perseus question integration.",
+ },
+ },
+ layout: "fullscreen",
+ },
+};
+
+export default meta;
+
+type Story = StoryObj;
+
+export const Default: Story = {};
+```
+
+---
+
+### Task 12: Test Full Game Flow
+- **What**: Play through entire game to verify everything works
+- **Why**: Integration testing
+- **Implementation notes**:
+ - Start game
+ - Go through story
+ - Play game
+ - Answer questions
+ - Verify all screens
+ - Check audio
+ - Test mute
+- **Files affected**:
+ - N/A (testing task)
+- **Acceptance criteria**:
+ - Full game flow works
+ - All screens display
+ - Questions work
+ - Audio works
+ - No console errors
+ - Game plays identically to original
+
+---
+
+### Task 13: Remove Old Files (Optional)
+- **What**: Remove original files from __docs__ now that new version works
+- **Why**: Clean up, avoid confusion
+- **Implementation notes**:
+ - **ONLY do this if new version is fully working**
+ - Delete math-blaster files from __docs__
+ - Keep one commit that can be reverted if needed
+- **Files affected**:
+ - Deleted: `__docs__/math-blaster-game.stories.tsx`
+ - Deleted: `__docs__/math-blaster-utils.ts`
+ - Deleted: `__docs__/math-blaster-game.module.css`
+ - Deleted: (assets already moved in Phase 1)
+- **Acceptance criteria**:
+ - Old files removed
+ - New version works
+ - Can rollback if needed
+
+---
+
+## Component Structure After This Phase
+
+```
+games/crash-course/
+├── components/
+│ ├── StartScreen.tsx (~30 lines)
+│ ├── StoryScreen.tsx (~40 lines)
+│ ├── HUD.tsx (~40 lines)
+│ ├── QuestionOverlay.tsx (~100 lines)
+│ ├── VictoryScreen.tsx (~30 lines)
+│ ├── GameOverScreen.tsx (~30 lines)
+│ ├── MuteButton.tsx (~20 lines)
+│ ├── BenevolenceMessage.tsx (~10 lines)
+│ └── index.ts (~10 lines)
+├── CrashCourseGame.tsx (~150 lines)
+├── crash-course.stories.tsx (~20 lines)
+└── ... (engine files from Phase 2)
+```
+
+---
+
+## Testing Considerations
+
+After this phase:
+1. **Visual Testing**: All screens display correctly
+2. **Interaction Testing**: Buttons and input work
+3. **Perseus Integration**: Questions render and score correctly
+4. **Audio**: Music plays, transitions work, mute works
+5. **Performance**: Still 60fps, no jank
+6. **Baseline Tests**: Compare against Phase 0 tests
+
+---
+
+## Benefits After This Phase
+
+- ✅ **Clean React components** - Each screen is separate
+- ✅ **Thin wrapper** - Main component is < 200 lines
+- ✅ **Perseus integration works** - Questions render and score
+- ✅ **Game fully playable** - All functionality restored
+- ✅ **Performance good** - 60fps maintained
+- ✅ **Maintainable** - Clear separation of concerns
+
+---
+
+## Next Phase
+
+**Phase 4**: Add documentation, verify tests pass, finalize everything.
+
+The refactoring is almost complete! 🎉
diff --git a/packages/perseus/src/games/crash-course/plans/PHASE_4_documentation_polish.md b/packages/perseus/src/games/crash-course/plans/PHASE_4_documentation_polish.md
new file mode 100644
index 00000000000..9a26b7fa87a
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/PHASE_4_documentation_polish.md
@@ -0,0 +1,891 @@
+# Phase 4: Documentation & Polish
+
+**Part of**: [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+
+**Goal**: Document the game architecture, add code comments, verify everything works correctly, and polish the implementation.
+
+## Tasks
+
+### Task 1: Write Main README
+- **What**: Create comprehensive README for the Crash Course game
+- **Why**: Help developers understand the architecture and how to modify/extend the game
+- **Implementation notes**:
+ - Explain the game engine architecture
+ - Document the React ↔ Engine communication pattern
+ - Provide examples of common modifications
+ - Include screenshots/diagrams
+ - Link to related documentation
+- **Files affected**:
+ - New: `packages/perseus/src/games/crash-course/README.md`
+- **Acceptance criteria**:
+ - Architecture clearly explained
+ - Common tasks documented (add sprite, change mechanics, etc.)
+ - Diagrams showing component relationships
+ - Code examples for extending the game
+
+**README structure:**
+```markdown
+# Crash Course - Educational Endless Runner Game
+
+## Overview
+Educational endless runner game where players answer math questions while avoiding obstacles...
+
+## Architecture
+
+### Game Engine Pattern
+```
+CrashCourseEngine (60fps) React UI (10-15fps)
+├── Game Loop ├── Canvas wrapper
+├── Physics & Collision ├── UI Screens
+├── Sprite Animation ├── HUD
+└── Perseus Integration └── Question Overlay
+```
+
+### Why This Architecture?
+- **Separation of concerns**: Game logic in pure TypeScript, UI in React
+- **Performance**: 60fps game loop independent of React rendering
+- **Testability**: Engine can be unit tested without React
+- **Reusability**: Systems can be shared across games
+
+## Key Systems
+
+### CrashCourseEngine
+Main game engine class...
+
+### SpriteManager
+Handles multi-entity sprite animations...
+
+### RenderSystem
+Canvas drawing utilities...
+
+### AudioSystem
+Music and sound effect management...
+
+### Perseus Integration
+How the game presents questions and handles answers...
+
+## Common Tasks
+
+### Adding a New Sprite
+```typescript
+await spriteManager.create("my-sprite", {
+ frames: [sprite1, sprite2, sprite3],
+ animations: {
+ idle: {frames: [0], loop: true},
+ action: {frames: [1, 2], fps: 10, loop: false},
+ },
+ position: {x: 100, y: 200},
+ size: {width: 50, height: 50},
+});
+```
+
+### Modifying Game Mechanics
+To change obstacle spawn rate...
+To add a new power-up...
+
+### Adding New Question Types
+Questions are generated in `crash-course-utils.ts`...
+
+## File Structure
+```
+games/crash-course/
+├── engine/ # Game engine core
+├── systems/ # Reusable systems
+├── sprites/ # Sprite animation
+├── components/ # React UI components
+└── assets/ # Images and audio
+```
+
+## Testing
+- Run tests: `pnpm --filter perseus test games/crash-course`
+- See baseline tests in `__tests__/crash-course.test.tsx`
+
+## Performance
+- Target: 60fps game loop, 10-15fps UI updates
+- See PERFORMANCE_BASELINE.md for metrics
+
+## Future Extensions
+- This pattern works for other game types (platformers, puzzles, etc.)
+- Reusable systems in `games/shared/` when game #2 needs them
+```
+
+### Task 2: Document Engine API
+- **What**: Add comprehensive JSDoc comments to engine classes
+- **Why**: Make the engine API self-documenting for future developers
+- **Implementation notes**:
+ - Document all public methods with JSDoc
+ - Explain parameters, return values, and side effects
+ - Add usage examples in comments
+ - Document the lifecycle (init → start → update → render → stop)
+- **Files affected**:
+ - `packages/perseus/src/games/crash-course/engine/crash-course-engine.ts`
+ - `packages/perseus/src/games/crash-course/engine/game-types.ts`
+- **Acceptance criteria**:
+ - All public APIs have JSDoc comments
+ - Examples provided for complex methods
+ - Lifecycle clearly documented
+ - IDE autocomplete shows helpful documentation
+
+**Example JSDoc:**
+```typescript
+/**
+ * Main game engine for Crash Course.
+ *
+ * Runs a 60fps game loop independent of React, handling physics, collision detection,
+ * sprite animation, and Perseus question integration.
+ *
+ * @example
+ * ```typescript
+ * const engine = new CrashCourseEngine({
+ * canvas: canvasElement,
+ * onUIUpdate: (state) => setGameState(state),
+ * });
+ *
+ * await engine.init(); // Load assets
+ * engine.start(); // Begin game loop
+ * // Later...
+ * engine.stop(); // Clean up
+ * ```
+ */
+export class CrashCourseEngine {
+ /**
+ * Initialize the game engine and load all assets.
+ *
+ * Must be called before start(). Loads sprites, audio, and sets up systems.
+ *
+ * @returns Promise that resolves when all assets are loaded
+ * @throws Error if canvas is not available or assets fail to load
+ */
+ async init(): Promise { /* ... */ }
+
+ /**
+ * Start the game loop.
+ *
+ * Begins the 60fps requestAnimationFrame loop. Call after init() completes.
+ * The game will begin in the "start" state showing the start screen.
+ */
+ start(): void { /* ... */ }
+
+ /**
+ * Submit an answer to the current Perseus question.
+ *
+ * @param correct - Whether the answer was correct
+ * @param earnedPoints - Points earned (usually 1 for correct, 0 for incorrect)
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void { /* ... */ }
+}
+```
+
+### Task 3: Document Systems
+- **What**: Add documentation for each system (Render, Audio, Assets, Sprites)
+- **Why**: Explain how systems work and how to use/extend them
+- **Implementation notes**:
+ - JSDoc comments for all public methods
+ - README in systems/ folder explaining system architecture
+ - Document design patterns used
+ - Explain how systems interact
+- **Files affected**:
+ - `packages/perseus/src/games/crash-course/systems/render-system.ts`
+ - `packages/perseus/src/games/crash-course/systems/audio-system.ts`
+ - `packages/perseus/src/games/crash-course/systems/asset-loader.ts`
+ - New: `packages/perseus/src/games/crash-course/systems/README.md`
+- **Acceptance criteria**:
+ - All systems have JSDoc comments
+ - Systems README explains overall architecture
+ - Design patterns documented
+ - Examples of extending systems
+
+**Systems README structure:**
+```markdown
+# Game Systems
+
+Reusable systems for game functionality.
+
+## RenderSystem
+Handles canvas drawing operations...
+
+## AudioSystem
+Manages music tracks and sound effects...
+
+## AssetLoader
+Loads and caches images and audio files...
+
+## Design Patterns
+- **Dependency Injection**: Systems receive dependencies in constructor
+- **Single Responsibility**: Each system handles one concern
+- **Composition over Inheritance**: Engine composes systems rather than inheriting
+
+## Future Reusability
+When building game #2, these systems can be moved to `games/shared/systems/`...
+```
+
+### Task 4: Document Sprite System
+- **What**: Document the sprite animation system in detail
+- **Why**: This is a reusable system that future games will use
+- **Implementation notes**:
+ - Comprehensive JSDoc for SpriteAnimator, AnimatedSprite, SpriteManager
+ - Document animation configuration format
+ - Provide examples for common use cases
+ - Explain layer-based rendering
+ - Document sprite effects (shake, opacity, etc.)
+- **Files affected**:
+ - `packages/perseus/src/games/crash-course/sprites/sprite-animator.ts`
+ - `packages/perseus/src/games/crash-course/sprites/animated-sprite.ts`
+ - `packages/perseus/src/games/crash-course/sprites/sprite-manager.ts`
+ - New: `packages/perseus/src/games/crash-course/sprites/README.md`
+- **Acceptance criteria**:
+ - All classes fully documented
+ - Animation config format explained
+ - Examples for: basic sprite, multi-animation sprite, effects, layers
+ - Performance considerations documented
+
+**Sprite README structure:**
+```markdown
+# Sprite Animation System
+
+Multi-entity sprite animation system for 2D games.
+
+## Architecture
+
+```
+SpriteManager
+├── AnimatedSprite #1
+│ └── SpriteAnimator
+├── AnimatedSprite #2
+│ └── SpriteAnimator
+└── AnimatedSprite #3
+ └── SpriteAnimator
+```
+
+## Quick Start
+
+### Single Sprite
+```typescript
+const animator = new SpriteAnimator();
+await animator.loadFrames([img1, img2, img3]);
+animator.addAnimation("walk", [0, 1, 2], {fps: 10, loop: true});
+animator.play("walk");
+```
+
+### Multiple Sprites (Manager)
+```typescript
+const manager = new SpriteManager(assetLoader);
+
+await manager.create("player", {
+ frames: ["run1.png", "run2.png"],
+ animations: {run: {frames: [0, 1], fps: 8}},
+});
+
+await manager.create("enemy", {
+ frames: ["alien1.png", "alien2.png"],
+ animations: {float: {frames: [0, 1], fps: 4}},
+});
+
+// In game loop
+manager.updateAll(deltaTime);
+manager.drawByLayers(ctx, ["background", "entities", "effects"]);
+```
+
+## Animation Configuration
+```typescript
+type AnimationConfig = {
+ frames: number[]; // Frame indices
+ fps?: number; // Default: 8
+ loop?: boolean; // Default: true
+ onComplete?: () => void;
+};
+```
+
+## Effects
+- Shake effect: `sprite.animator.setEffect({type: "shake", intensity: 5})`
+- Opacity: `sprite.opacity = 0.5`
+
+## Layer-Based Rendering
+Sprites can be assigned to layers for draw order control...
+
+## Performance
+- Spritesheets recommended for many frames
+- Limit active sprites to ~50 for 60fps
+- Use object pooling for frequently spawned sprites
+
+## Future Games
+This system can be moved to `games/shared/sprites/` when needed by other games.
+```
+
+### Task 5: Document React Components
+- **What**: Add JSDoc comments and prop documentation to React components
+- **Why**: Make UI components easy to understand and modify
+- **Implementation notes**:
+ - Document all component props with TypeScript
+ - Add JSDoc comments explaining component purpose
+ - Document callback patterns
+ - Explain when components render
+- **Files affected**:
+ - All files in `packages/perseus/src/games/crash-course/components/`
+- **Acceptance criteria**:
+ - All props have TypeScript types and descriptions
+ - Component purpose documented
+ - Rendering behavior explained
+ - Examples for complex components
+
+**Example component documentation:**
+```typescript
+/**
+ * Displays the current score, lives, and time remaining during gameplay.
+ *
+ * Updates 10-15 times per second via throttled callbacks from the game engine.
+ *
+ * @param score - Current player score (0-999+)
+ * @param lives - Remaining lives (0-3)
+ * @param gameTime - Formatted time string (e.g., "4:23")
+ */
+export function HUD({
+ score,
+ lives,
+ gameTime,
+}: {
+ score: number;
+ lives: number;
+ gameTime: string;
+}): React.ReactElement {
+ /* ... */
+}
+```
+
+### Task 6: Document Perseus Integration
+- **What**: Document how Perseus questions are integrated
+- **Why**: This pattern will be reused by future educational games
+- **Implementation notes**:
+ - Document the PerseusGameEngine interface implementation
+ - Explain question lifecycle (spawn → present → answer → despawn)
+ - Document how to add new question types
+ - Explain answer validation flow
+- **Files affected**:
+ - `packages/perseus/src/games/crash-course/engine/crash-course-engine.ts` (Perseus methods)
+ - `packages/perseus/src/games/crash-course/utils/crash-course-utils.ts`
+ - `packages/perseus/src/games/shared/perseus/PerseusGameEngine.ts`
+- **Acceptance criteria**:
+ - PerseusGameEngine interface documented
+ - Question lifecycle explained
+ - Examples for adding question types
+ - Answer validation flow documented
+
+**Perseus integration docs:**
+```typescript
+/**
+ * Perseus integration interface for educational games.
+ *
+ * All games that integrate Perseus questions should implement this interface
+ * to ensure consistent behavior.
+ */
+export interface PerseusGameEngine {
+ /**
+ * Get the currently active Perseus question.
+ *
+ * @returns The current question, or null if no question is active
+ */
+ getCurrentQuestion(): PerseusItem | null;
+
+ /**
+ * Submit an answer to the current question.
+ *
+ * @param correct - Whether the answer was correct
+ * @param earnedPoints - Points earned (typically 1 for correct, 0 for incorrect)
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void;
+
+ /**
+ * Register a callback for when the question changes.
+ *
+ * The game should call this callback when:
+ * - A new question is presented
+ * - A question is answered and despawned
+ * - The game ends
+ *
+ * @param callback - Function to call with the new question (or null)
+ */
+ onQuestionChange(callback: (question: PerseusItem | null) => void): void;
+}
+```
+
+### Task 7: Add Inline Code Comments
+- **What**: Add explanatory comments for complex logic
+- **Why**: Make the code easier to understand and modify
+- **Implementation notes**:
+ - Comment complex algorithms (collision detection, spawning logic)
+ - Explain non-obvious choices (magic numbers, timing values)
+ - Document edge cases and their handling
+ - Add TODO comments for future improvements
+- **Files affected**:
+ - All TypeScript files with complex logic
+- **Acceptance criteria**:
+ - Complex algorithms have explanatory comments
+ - Magic numbers explained (e.g., why SPAWN_INTERVAL = 5000)
+ - Edge cases documented
+ - Future improvements noted with TODO comments
+
+**Example inline comments:**
+```typescript
+// Check if obstacle is in the collision zone AND player hasn't answered the question
+// The collision zone starts before the character position to give time to answer
+if (
+ obstacle.x < COLLISION_ZONE_X && // Obstacle has entered the zone
+ obstacle.x + OBSTACLE_WIDTH > characterX && // Still overlapping
+ !obstacle.answered // Question hasn't been answered
+) {
+ // Trigger question presentation
+ this.currentQuestion = obstacle.question;
+ this.notifyQuestionChange();
+}
+
+// Game speed increases every 30 seconds to add difficulty
+// Caps at 2x base speed to keep game playable
+if (gameTimeSeconds % 30 === 0 && this.scrollSpeed < SCROLL_SPEED * 2) {
+ this.scrollSpeed += 0.2; // 10% increase
+}
+```
+
+### Task 8: Create Migration Guide
+- **What**: Document the refactoring changes for reviewers
+- **Why**: Help code reviewers understand what changed and why
+- **Implementation notes**:
+ - Before/after architecture comparison
+ - List of moved files
+ - Breaking changes (if any)
+ - Testing strategy explanation
+- **Files affected**:
+ - New: `MIGRATION.md` (in repo root, temporary)
+- **Acceptance criteria**:
+ - Clear before/after comparison
+ - All file moves documented
+ - Testing approach explained
+ - Can be removed after merge
+
+**Migration guide structure:**
+```markdown
+# Crash Course Refactoring - Migration Guide
+
+## What Changed
+
+### Architecture
+**Before**: Monolithic React component with game loop in useEffect
+**After**: Custom game engine (pure TypeScript) + thin React UI wrapper
+
+### File Organization
+**Before**: All files in `__docs__/`
+**After**: Organized in `games/crash-course/`
+
+## Moved Files
+
+| Old Location | New Location |
+|--------------|--------------|
+| `__docs__/math-blaster-game.stories.tsx` | `games/crash-course/crash-course.stories.tsx` |
+| `__docs__/math-blaster-utils.ts` | `games/crash-course/utils/crash-course-utils.ts` |
+| `__docs__/run1.png` ... | `games/crash-course/assets/sprites/character/` |
+
+## Breaking Changes
+- **None** - This is an internal refactoring, no public API changes
+
+## Testing Strategy
+- Phase 0 established baseline tests before refactoring
+- All tests passing with new architecture
+- Performance metrics verified (see PERFORMANCE_BASELINE.md)
+
+## Review Checklist
+- [ ] Architecture makes sense (engine vs React separation)
+- [ ] File organization is clear
+- [ ] Tests cover critical functionality
+- [ ] Performance is maintained or improved
+- [ ] Code is well-documented
+```
+
+### Task 9: Run Full Test Suite
+- **What**: Run all tests and verify they pass
+- **Why**: Ensure refactoring didn't break anything
+- **Implementation notes**:
+ - Run: `pnpm --filter perseus test games/crash-course`
+ - Verify all baseline tests pass
+ - Check for any test warnings
+ - Fix any failing tests
+- **Files affected**:
+ - Test files in `packages/perseus/src/games/crash-course/__tests__/`
+- **Acceptance criteria**:
+ - All tests passing
+ - No test warnings
+ - Code coverage acceptable (>80% for engine core)
+
+### Task 10: Verify Performance Baselines
+- **What**: Compare current performance to Phase 0 baselines
+- **Why**: Ensure refactoring maintained or improved performance
+- **Implementation notes**:
+ - Use Chrome DevTools Performance tab
+ - Record 30-second gameplay session
+ - Compare FPS, memory, load time to PERFORMANCE_BASELINE.md
+ - Document any improvements or regressions
+- **Files affected**:
+ - Update: `PERFORMANCE_BASELINE.md`
+- **Acceptance criteria**:
+ - FPS maintained or improved (target: 58-60fps)
+ - Memory usage stable (no leaks)
+ - Load time comparable or better
+ - Findings documented
+
+**Performance comparison format:**
+```markdown
+## Phase 4 Results (After Refactoring)
+
+### Frame Rate
+- Average FPS: 59-60 fps ✅ (was: 58-60)
+- Minimum FPS: 57 fps ✅ (was: 55)
+- Frame time: 16-17ms ✅ (unchanged)
+
+### Load Time
+- Asset loading: 1.8 seconds ✅ (was: 2.1s, improved!)
+- Game initialization: 280ms ✅ (was: 320ms)
+- Time to interactive: 2.1 seconds ✅ (was: 2.5s)
+
+### Memory
+- Initial: 42MB ✅ (was: 45MB, slightly better)
+- After 1 minute: 48MB ✅ (was: 52MB)
+- After 5 minutes: 52MB ✅ (was: 58MB)
+- Memory more stable with engine architecture
+
+## Analysis
+✅ All metrics maintained or improved
+✅ Game loop separation improved frame consistency
+✅ Asset loading optimization reduced initial load time
+```
+
+### Task 11: Manual Gameplay Testing
+- **What**: Play through the entire game and verify all features work
+- **Why**: Catch visual, audio, or gameplay issues tests might miss
+- **Implementation notes**:
+ - Test all game states: start → story → playing → victory/game over
+ - Verify all animations play correctly
+ - Check audio (music transitions, sound effects)
+ - Test edge cases: run out of lives, answer all questions correctly
+ - Verify Perseus widget rendering and answer validation
+ - Test on different screen sizes
+- **Files affected**:
+ - New: `MANUAL_TEST_CHECKLIST.md` (checklist during testing)
+- **Acceptance criteria**:
+ - All game states working correctly
+ - Animations smooth and correct
+ - Audio plays at right times
+ - Perseus questions work correctly
+ - No visual glitches
+ - Works on mobile/tablet sizes
+
+**Manual test checklist:**
+```markdown
+# Manual Test Checklist
+
+## Start Screen
+- [ ] Title displays correctly
+- [ ] Start button responds to click
+- [ ] Mute/unmute toggle works
+
+## Story Screens
+- [ ] All 7 story pages display
+- [ ] Next button advances pages
+- [ ] Can skip to game
+
+## Gameplay
+- [ ] Character runs smoothly
+- [ ] Jump animation plays
+- [ ] Obstacles spawn regularly
+- [ ] Questions appear on obstacles
+- [ ] Can answer questions with Perseus widget
+- [ ] Correct answers: obstacle disappears, score increases
+- [ ] Wrong answers: lose life, impact animation plays
+- [ ] Parallax scrolling works
+- [ ] Cool mode activates after correct answers
+- [ ] Timer counts down correctly
+
+## Alien Abduction
+- [ ] Aliens spawn when life lost
+- [ ] Abduction animation plays
+- [ ] Benevolence message appears
+
+## Car Bonus
+- [ ] Car appears on final question
+- [ ] Bonus screen displays
+- [ ] Can continue to victory
+
+## Victory Screen
+- [ ] Shows when timer reaches 0
+- [ ] Final score displayed
+- [ ] Play again button works
+
+## Game Over Screen
+- [ ] Shows when all lives lost
+- [ ] Play again button works
+
+## Audio
+- [ ] Start screen music plays
+- [ ] Story music plays
+- [ ] Gameplay music plays
+- [ ] Music transitions smoothly
+- [ ] Game over music plays
+- [ ] Mute toggle affects all audio
+
+## Responsive
+- [ ] Works on desktop (800x600+)
+- [ ] Works on tablet
+- [ ] Works on mobile (touch controls)
+```
+
+### Task 12: Code Cleanup
+- **What**: Remove debug code, console.logs, and unused imports
+- **Why**: Clean code for production
+- **Implementation notes**:
+ - Remove all console.log statements
+ - Remove commented-out code
+ - Remove unused imports
+ - Run linter and fix all warnings
+ - Run Prettier to format code
+- **Files affected**:
+ - All TypeScript/TSX files
+- **Acceptance criteria**:
+ - No console.log statements (except intentional errors)
+ - No commented-out code
+ - No unused imports
+ - Linter passes with no warnings
+ - Code formatted with Prettier
+
+**Cleanup commands:**
+```bash
+# Remove console.logs (review each manually)
+grep -r "console.log" packages/perseus/src/games/crash-course/
+
+# Fix linting
+pnpm lint --fix
+
+# Format code
+pnpm prettier packages/perseus/src/games/crash-course/ --write
+
+# Type check
+pnpm tsc
+```
+
+### Task 13: Final Code Review
+- **What**: Review all code changes one final time
+- **Why**: Catch any issues before submitting PR
+- **Implementation notes**:
+ - Review git diff of all changes
+ - Check for any missed TODOs or FIXMEs
+ - Verify naming consistency
+ - Check for any hardcoded values that should be constants
+ - Review error handling
+- **Files affected**:
+ - All changed files
+- **Acceptance criteria**:
+ - All changes reviewed
+ - Naming is consistent
+ - No hardcoded magic values
+ - Error handling is proper
+ - Ready for PR
+
+### Task 14: Update Storybook Story
+- **What**: Update the Storybook story for the refactored game
+- **Why**: Ensure developers can preview the game in Storybook
+- **Implementation notes**:
+ - Update story file to import from new locations
+ - Add documentation to the story
+ - Add controls for testing different scenarios
+ - Verify story renders correctly in Storybook
+- **Files affected**:
+ - `packages/perseus/src/games/crash-course/crash-course.stories.tsx`
+- **Acceptance criteria**:
+ - Story imports from correct locations
+ - Game renders in Storybook
+ - Controls work (if any)
+ - Documentation explains the game
+
+**Updated story structure:**
+```typescript
+import type {Meta, StoryObj} from "@storybook/react";
+
+import {CrashCourseGame} from "./components/crash-course-game";
+
+/**
+ * # Crash Course
+ *
+ * Educational endless runner game where players answer math questions while avoiding obstacles.
+ *
+ * ## Architecture
+ * - Custom game engine (60fps) separate from React
+ * - Sprite animation system for character and obstacles
+ * - Perseus integration for questions
+ *
+ * See `games/crash-course/README.md` for full documentation.
+ */
+const meta: Meta = {
+ component: CrashCourseGame,
+ title: "Games/Crash Course",
+};
+
+export default meta;
+type Story = StoryObj;
+
+export const Default: Story = {};
+```
+
+### Task 15: Create Pull Request Checklist
+- **What**: Create checklist for the PR description
+- **Why**: Ensure thorough review and nothing is missed
+- **Implementation notes**:
+ - List all major changes
+ - Reference baseline tests and performance metrics
+ - Link to planning documents
+ - Highlight areas needing careful review
+- **Files affected**:
+ - New: `PR_CHECKLIST.md` (temporary, for PR description)
+- **Acceptance criteria**:
+ - All changes listed
+ - Testing approach explained
+ - Review areas highlighted
+ - Can copy into PR description
+
+**PR checklist template:**
+```markdown
+# Crash Course Refactoring
+
+## Summary
+Refactored Crash Course (formerly Math Blaster) educational game from monolithic React component to custom game engine architecture.
+
+## Changes
+
+### Architecture
+- ✅ Custom game engine (60fps, pure TypeScript)
+- ✅ Multi-entity sprite animation system
+- ✅ Separated game logic from React UI
+- ✅ Perseus integration interface
+
+### File Organization
+- ✅ Moved from `__docs__/` to `games/crash-course/`
+- ✅ Organized assets into folders (sprites, backgrounds, ui, audio)
+- ✅ Extracted 13 React UI components
+- ✅ Created reusable systems (Render, Audio, Assets)
+
+### Testing
+- ✅ 15+ baseline tests written and passing
+- ✅ Performance baselines verified (maintained/improved)
+- ✅ Manual gameplay testing completed
+
+### Documentation
+- ✅ Comprehensive README
+- ✅ JSDoc comments on all public APIs
+- ✅ System documentation
+- ✅ Inline comments for complex logic
+
+## Testing Strategy
+See PHASE_0_testing_foundation.md and PERFORMANCE_BASELINE.md
+
+## Review Focus Areas
+1. **Engine API design** - Is it clean and extensible?
+2. **Sprite system** - Will it work for future games?
+3. **Perseus integration** - Is the pattern reusable?
+4. **Performance** - Verify 60fps in DevTools
+5. **Manual testing** - Play the game!
+
+## References
+- [CRASH_COURSE_CONCEPT.md](./CRASH_COURSE_CONCEPT.md)
+- [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+- [REFACTORING_PLAN_SUMMARY.md](./REFACTORING_PLAN_SUMMARY.md)
+
+## Checklist
+- [ ] All tests passing
+- [ ] Linter passing
+- [ ] TypeScript compiling
+- [ ] Performance verified
+- [ ] Manual testing completed
+- [ ] Documentation complete
+- [ ] Storybook story working
+```
+
+## Testing Considerations
+
+### Documentation Quality Checks
+- **Clarity**: Can a new developer understand the architecture?
+- **Completeness**: Are all public APIs documented?
+- **Examples**: Do complex features have usage examples?
+- **Accuracy**: Do docs match implementation?
+
+### Verification Steps
+1. Run `pnpm test` - all tests pass
+2. Run `pnpm lint` - no warnings
+3. Run `pnpm tsc` - no type errors
+4. Run `pnpm storybook` - game renders correctly
+5. Manual gameplay test - all features work
+6. Performance test - 60fps maintained
+
+## Deliverables
+
+After this phase, you should have:
+1. ✅ Main README with architecture explanation
+2. ✅ Engine API fully documented (JSDoc)
+3. ✅ All systems documented
+4. ✅ Sprite system documentation
+5. ✅ React components documented
+6. ✅ Perseus integration documented
+7. ✅ Inline comments for complex logic
+8. ✅ Migration guide for reviewers
+9. ✅ All tests passing
+10. ✅ Performance verified
+11. ✅ Manual testing completed
+12. ✅ Code cleaned up
+13. ✅ Final review done
+14. ✅ Storybook story updated
+15. ✅ PR checklist ready
+
+## Benefits
+
+- **Maintainability**: Well-documented code is easier to modify
+- **Knowledge Transfer**: New developers can understand the system
+- **Reusability**: Clear documentation makes it easier to adapt for other games
+- **Quality**: Thorough testing and review catches issues
+- **Confidence**: Ready to merge with confidence
+
+## Time Estimate
+
+- Main README: 45 minutes
+- Engine API docs: 30 minutes
+- Systems docs: 30 minutes
+- Sprite system docs: 30 minutes
+- Component docs: 20 minutes
+- Perseus docs: 20 minutes
+- Inline comments: 30 minutes
+- Migration guide: 15 minutes
+- Test suite run: 10 minutes
+- Performance verification: 20 minutes
+- Manual testing: 30 minutes
+- Code cleanup: 20 minutes
+- Final review: 30 minutes
+- Storybook update: 15 minutes
+- PR checklist: 10 minutes
+
+**Total: 4.5-5 hours**
+
+## Success Criteria
+
+- [ ] README explains architecture clearly
+- [ ] All public APIs have JSDoc documentation
+- [ ] Systems are documented with examples
+- [ ] Sprite system fully documented
+- [ ] React components documented
+- [ ] Perseus integration pattern documented
+- [ ] Complex logic has inline comments
+- [ ] Migration guide created
+- [ ] All tests passing
+- [ ] Performance verified (60fps)
+- [ ] Manual testing checklist completed
+- [ ] Code cleaned (no console.logs, unused imports)
+- [ ] Final code review done
+- [ ] Storybook story working
+- [ ] PR checklist ready
+- [ ] Ready to submit PR with confidence
+
+---
+
+**After this phase**, the refactoring is complete and ready for code review! 🎉
diff --git a/packages/perseus/src/games/crash-course/plans/README.md b/packages/perseus/src/games/crash-course/plans/README.md
new file mode 100644
index 00000000000..30149d60f1a
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/README.md
@@ -0,0 +1,44 @@
+# Crash Course Refactoring Plans
+
+This folder contains the planning documents for refactoring the Crash Course (formerly Math Blaster) educational game.
+
+## Core Documents
+
+- **[CRASH_COURSE_CONCEPT.md](./CRASH_COURSE_CONCEPT.md)** - High-level architecture vision and game engine design
+- **[CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)** - Overview of the 5-phase refactoring plan
+- **[REFACTORING_PLAN_SUMMARY.md](./REFACTORING_PLAN_SUMMARY.md)** - Explains what changed from the original plan and why
+
+## Phase Documents
+
+- **[PHASE_0_testing_foundation.md](./PHASE_0_testing_foundation.md)** - Testing infrastructure and baselines (8 tasks, 2-3 hours)
+- **[PHASE_1_setup_assets_architecture.md](./PHASE_1_setup_assets_architecture.md)** - Directory setup and API design (15 tasks, 2-3 hours)
+- **[PHASE_2_build_engine.md](./PHASE_2_build_engine.md)** - Build game engine and sprite system (20 tasks, 5-7 hours)
+- **[PHASE_3_ui_components.md](./PHASE_3_ui_components.md)** - React UI components and integration (13 tasks, 2-3 hours)
+- **[PHASE_4_documentation_polish.md](./PHASE_4_documentation_polish.md)** - Documentation and polish (15 tasks, 4.5-5 hours)
+
+## Total Effort
+
+**71 tasks across 5 phases, 16-21 hours**
+
+## Key Decisions
+
+1. **Custom Game Engine**: Pure TypeScript engine separate from React (eliminates hook complexity)
+2. **Multi-Entity Sprite System**: Built from the start to prevent future refactoring
+3. **Testing First**: Phase 0 establishes baselines before any refactoring
+4. **Reusable Systems**: RenderSystem, AudioSystem, AssetLoader, Perseus integration interface
+5. **YAGNI Principle**: Build what's needed now, extract to shared/ when game #2 needs it
+
+## Getting Started
+
+1. Read [REFACTORING_PLAN_SUMMARY.md](./REFACTORING_PLAN_SUMMARY.md) for context
+2. Review [CRASH_COURSE_CONCEPT.md](./CRASH_COURSE_CONCEPT.md) for architecture
+3. Start with [PHASE_0_testing_foundation.md](./PHASE_0_testing_foundation.md)
+
+## Documentation Created During Refactoring
+
+As you work through the phases, additional documentation will be created in this folder:
+- `PERFORMANCE_BASELINE.md` - Performance metrics (Phase 0)
+- `ORIGINAL_BEHAVIOR.md` - Current game behavior documentation (Phase 0)
+- `MANUAL_TEST_CHECKLIST.md` - Manual testing checklist (Phase 4)
+- `MIGRATION.md` - Refactoring changes for reviewers (Phase 4, temporary)
+- `PR_CHECKLIST.md` - Pull request checklist (Phase 4, temporary)
diff --git a/packages/perseus/src/games/crash-course/plans/REFACTORING_PLAN_SUMMARY.md b/packages/perseus/src/games/crash-course/plans/REFACTORING_PLAN_SUMMARY.md
new file mode 100644
index 00000000000..9638b40e9b0
--- /dev/null
+++ b/packages/perseus/src/games/crash-course/plans/REFACTORING_PLAN_SUMMARY.md
@@ -0,0 +1,216 @@
+# Crash Course Refactoring Plan - Summary
+
+## What Changed After AI Review
+
+The original plan was to refactor the React component by extracting hooks, components, and optimizing state management. After the AI subagent review and discussing game engine architecture, **we've pivoted to a much better approach**.
+
+## New Architecture: Custom Game Engine
+
+### The Problem
+The original plan would have struggled with:
+- React + requestAnimationFrame hook complexity
+- Dual state/ref patterns for performance
+- Complex dependency management in useEffect
+- Game loop conflicts with React rendering
+
+### The Solution
+**Build a custom game engine in pure TypeScript**, separate from React:
+
+```
+┌─────────────────────────────────────┐
+│ React (UI Only) │
+│ - Screens, HUD, Perseus questions │
+│ - Updates 10-15fps │
+└────────────┬────────────────────────┘
+ │ callbacks
+ ▼
+┌─────────────────────────────────────┐
+│ CrashCourseEngine (Game Logic) │
+│ - 60fps game loop │
+│ - Physics, collision, rendering │
+│ - Pure TypeScript, no React │
+└─────────────────────────────────────┘
+```
+
+## Updated Plan Overview
+
+### Phase 0: Testing Foundation (NEW)
+**Why**: AI review identified "no testing" as critical issue
+- Write baseline tests before refactoring
+- Capture performance metrics
+- Document current behavior
+- **2-3 hours**
+
+### Phase 1: Setup & Engine Architecture
+**Was**: Just asset organization
+**Now**: Assets + design game engine API
+- Move assets to organized folders
+- Define engine interface and types
+- Design React ↔ Engine communication
+- **2-3 hours**
+
+### Phase 2: Build Game Engine
+**Was**: Extract hooks and game loop (complex)
+**Now**: Build the engine class (cleaner)
+- Create CrashCourseEngine class
+- Move game loop logic to engine.update()
+- Move canvas drawing to engine.render()
+- Build supporting systems (Render, Audio, Assets)
+- **5-7 hours** (most complex phase)
+
+### Phase 3: UI Components
+**Was**: Extract React components (11 tasks)
+**Now**: Create thin React wrapper (simpler)
+- React component becomes thin wrapper
+- Extract UI overlays (screens, HUD, questions)
+- Connect to engine via callbacks
+- **2-3 hours** (much simpler now)
+
+### Phase 4: Documentation
+**Was**: Documentation + complex state refactor
+**Now**: Just documentation (state is in engine)
+- Write README with architecture
+- Add code comments
+- Document systems
+- **2-3 hours**
+
+### Old Phase 4 (State Management)
+**Status**: ~~REMOVED~~ - Not needed with engine architecture!
+
+## Total Effort
+
+**Original Plan**: 14-20 hours (5 phases)
+**New Plan**: 13-19 hours (5 phases, but simpler)
+
+**More importantly**: Much cleaner result, no React hook complexity!
+
+## Key Benefits
+
+### Compared to Original Plan
+
+**Original**:
+- ❌ Extract game loop into complex useGameLoop hook
+- ❌ Manage 30+ state variables with useReducer
+- ❌ Fight React + requestAnimationFrame conflicts
+- ❌ Complex optimization phase needed
+
+**New**:
+- ✅ Game logic is pure TypeScript (simple, testable)
+- ✅ No React hook complexity
+- ✅ Clear separation: Engine = logic, React = UI
+- ✅ No optimization phase needed
+
+### For Future Games
+
+**Original plan**: Hard to reuse patterns
+**New plan**: Clear template for educational games
+
+Any future game can:
+1. Create `[GameName]Engine` class
+2. Implement game logic in pure TypeScript
+3. Use React for UI overlays
+4. Integrate Perseus questions the same way
+
+**Reusable systems**:
+- RenderSystem (canvas drawing)
+- AudioSystem (music management)
+- AssetLoader (image/audio loading)
+- Perseus integration pattern
+
+## Documents Created/Updated
+
+### Core Documents ✅
+- [CRASH_COURSE_CONCEPT.md](./CRASH_COURSE_CONCEPT.md) - Updated with engine architecture
+- [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md) - New 5-phase plan
+
+### Phase Documents
+- [PHASE_0_testing_foundation.md](./PHASE_0_testing_foundation.md) - ✅ NEW - Critical foundation
+- PHASE_1_setup_assets_architecture.md - 🔄 Needs update (add engine API design)
+- PHASE_2_build_engine.md - 🔄 Needs creation (core refactoring work)
+- PHASE_3_ui_components.md - 🔄 Needs update (simpler now)
+- PHASE_4_documentation_polish.md - 🔄 Needs update (remove state management)
+
+### Old Phase Documents (Reference Only)
+- ~~PHASE_1_setup_assets.md~~ - Original, kept for reference
+- ~~PHASE_2_ui_components.md~~ - Original, kept for reference
+- ~~PHASE_3_game_logic.md~~ - Original, kept for reference
+- ~~PHASE_4_state_management.md~~ - Original, kept for reference
+- ~~PHASE_5_documentation.md~~ - Original, kept for reference
+
+## What This Means for Implementation
+
+### Immediate Next Steps
+
+1. **Review updated concept** - Read CRASH_COURSE_CONCEPT.md to understand new architecture
+2. **Start with Phase 0** - Set up testing foundation (critical!)
+3. **Phase 1 design** - Design the engine API before building
+4. **Build incrementally** - Engine systems one at a time
+5. **Test continuously** - Use baseline tests to catch issues
+
+### Don't Need to Do
+
+- ❌ Complex useGameLoop hook extraction
+- ❌ useReducer for state management
+- ❌ useMemo/useCallback optimization
+- ❌ Consolidating 30+ state variables
+- ❌ Fighting React re-render issues
+
+### Do Need to Do
+
+- ✅ Design clean engine API
+- ✅ Move game logic to engine class
+- ✅ Create system classes (Render, Audio, Assets)
+- ✅ Build thin React wrapper
+- ✅ Connect with callbacks
+
+## Risk Mitigation
+
+### Original Plan Risks
+- Hook dependency management (HIGH)
+- useGameLoop complexity (HIGH)
+- State management timing (MEDIUM-HIGH)
+- Performance optimization (MEDIUM)
+
+### New Plan Risks
+- Engine API design (MEDIUM) - Mitigated by Phase 1 design work
+- Moving complex logic (MEDIUM) - Mitigated by baseline tests
+- Perseus integration (LOW) - Stays in React, minimal risk
+
+## Questions?
+
+### "Why is this better?"
+- Simpler: Game logic is plain TypeScript, no React complexity
+- Testable: Can unit test engine without React
+- Performant: 60fps game loop, React only updates UI
+- Reusable: Pattern for future educational games
+
+### "Is this more work?"
+- Similar hours (13-19 vs 14-20)
+- But much cleaner result
+- Less debugging of hook issues
+- Sets good precedent
+
+### "Can we still reuse things for future games?"
+- Yes! Even better than before
+- Systems (Render, Audio, Assets) can be shared
+- Engine pattern is clear template
+- Perseus integration is reusable
+
+### "What if we want to change it later?"
+- Engine is self-contained (easy to modify)
+- React UI is separate (can change independently)
+- Clear boundaries make changes safer
+
+## Ready to Start?
+
+**Recommended path**:
+
+1. ✅ Read updated [CRASH_COURSE_CONCEPT.md](./CRASH_COURSE_CONCEPT.md)
+2. ✅ Read [CRASH_COURSE_IMPLEMENTATION_PLAN.md](./CRASH_COURSE_IMPLEMENTATION_PLAN.md)
+3. 🚀 **Start with [PHASE_0_testing_foundation.md](./PHASE_0_testing_foundation.md)**
+4. Create feature branch: `git checkout -b refactor/crash-course-engine`
+5. Begin Phase 0 work
+
+**Or**: Ask questions, discuss concerns, review the plan more!
+
+The game engine architecture is a great fit for this refactoring and sets you up well for future educational games. 🎮
diff --git a/packages/perseus/src/games/shared/perseus/perseus-game-engine.ts b/packages/perseus/src/games/shared/perseus/perseus-game-engine.ts
new file mode 100644
index 00000000000..6e7aa64a8d2
--- /dev/null
+++ b/packages/perseus/src/games/shared/perseus/perseus-game-engine.ts
@@ -0,0 +1,87 @@
+/**
+ * Perseus Game Engine Interface
+ *
+ * Standard interface that all educational games must implement
+ * to integrate Perseus questions.
+ *
+ * This ensures consistent behavior across all games.
+ */
+import type {PerseusItem} from "@khanacademy/perseus-core";
+
+/**
+ * Interface for game engines that integrate Perseus questions
+ *
+ * All educational games should implement this interface to provide
+ * a consistent way for React components to interact with Perseus questions.
+ */
+export interface PerseusGameEngine {
+ /**
+ * Get the currently active Perseus question
+ *
+ * @returns The current question, or null if no question is active
+ */
+ getCurrentQuestion(): PerseusItem | null;
+
+ /**
+ * Submit an answer to the current question
+ *
+ * Called by React when the player submits an answer through the Perseus widget.
+ *
+ * @param correct - Whether the answer was correct
+ * @param earnedPoints - Points earned (typically 1 for correct, 0 for incorrect)
+ */
+ submitAnswer(correct: boolean, earnedPoints: number): void;
+
+ /**
+ * Register a callback for when the question changes
+ *
+ * The game engine should call this callback when:
+ * - A new question is presented to the player
+ * - A question is answered and removed
+ * - The game ends and all questions are cleared
+ *
+ * @param callback - Function to call with the new question (or null)
+ */
+ onQuestionChange(callback: (question: PerseusItem | null) => void): void;
+}
+
+/**
+ * Example usage:
+ *
+ * ```typescript
+ * class MyGameEngine implements PerseusGameEngine {
+ * private currentQuestion: PerseusItem | null = null;
+ * private callback: ((question: PerseusItem | null) => void) | null = null;
+ *
+ * getCurrentQuestion(): PerseusItem | null {
+ * return this.currentQuestion;
+ * }
+ *
+ * submitAnswer(correct: boolean, earnedPoints: number): void {
+ * // Handle answer in game logic
+ * if (correct) {
+ * this.score += earnedPoints;
+ * } else {
+ * this.lives -= 1;
+ * }
+ * this.currentQuestion = null;
+ * this.notifyQuestionChange();
+ * }
+ *
+ * onQuestionChange(callback: (question: PerseusItem | null) => void): void {
+ * this.callback = callback;
+ * }
+ *
+ * private presentQuestion(question: PerseusItem): void {
+ * this.currentQuestion = question;
+ * this.notifyQuestionChange();
+ * }
+ *
+ * private notifyQuestionChange(): void {
+ * if (this.callback) {
+ * this.callback(this.currentQuestion);
+ * }
+ * }
+ * }
+ * ```
+ */
diff --git a/story.md b/story.md
new file mode 100644
index 00000000000..daf4b0db326
--- /dev/null
+++ b/story.md
@@ -0,0 +1,33 @@
+# Heading
+
+$ alien-ai process --input message.txt --mode human literal
+
+[00:00.001] INFO: Parsing message from Sal Khan
+[00:00.023] WARN: Large context window detected
+[00:00.045] PARSE: Tokenizing input...
+
+TOKEN ANALYSIS:
+┌──────────────────┬─────────────────┬──────────────────────┐
+│ Token │ Classification │ Interpretation │
+├──────────────────┼─────────────────┼──────────────────────┤
+│ "khan" │ ENTITY │ → Sal Khan (person) │
+│ "keeps crashing" │ CRITICAL_EVENT │ → Collision (repeat) │
+│ │ │ → Must replicate │
+├──────────────────┼─────────────────┼──────────────────────┤
+│ "exercises" │ NOUN/DATABASE │ → Math problems │
+│ "running" │ VERB/STATUS │ → Locomotion OR │
+│ │ │ operational │
+│ Combined: │ ⚠️ AMBIGUOUS │ → Execute both │
+├──────────────────┼─────────────────┼──────────────────────┤
+│ "reach students" │ OBJECTIVE │ → Arrival required │
+│ "midnight" │ DEADLINE │ → 300s remaining │
+└──────────────────┴─────────────────┴──────────────────────┘
+
+[00:00.089] SOLVE: Generating optimal scenario...
+[00:00.134] EXEC: Deploying collision obstacles
+[00:00.156] EXEC: Initiating locomotion sequence
+[00:00.201] STATUS: Scenario active ✓
+
+[00:05.433] ⚠️ ALERT: Alien operators signaling abort
+[00:05.434] ERROR: Cannot safely terminate running scenario
+[00:05.435] FALLBACK: Emergency intervention protocol engaged