Play in browser: https://dareludum.github.io/ld44/play
Beam (https://opengameart.org/content/lasers-and-beams)
Zombie by Riley Gombart or ChessMasterRiley (https://opengameart.org/content/animated-top-down-zombie)
Creative Commons BY License: https://creativecommons.org/licenses/by/4.0/ Alien by MillionthVector (http://millionthvector.blogspot.de, https://opengameart.org/content/set-faction3-spaceships)
Creative Commons BY License: https://creativecommons.org/licenses/by/4.0/ Boss by MillionthVector (http://millionthvector.blogspot.de, https://opengameart.org/content/set-faction10-spacestations)
Sound effects are under Attribution 3.0 license: https://creativecommons.org/licenses/by/3.0/us/legalcode Credits to http://soundbible.com
Background music: "Eventide" Purple Planet Music https://www.purple-planet.com