There’s one UEFI-based game I have not mentioned: Maze, by Tim Lewis. He’s got multiple blog posts on how the code works. He just relicensed it to BSD:
https://uefi.blogspot.com/2017/04/maze-game-source-code.html
https://uefi.blogspot.com/search/label/Maze
https://svn.code.sf.net/p/syslibforuefi/code/trunk/
Look at the game/games tags for other UEFI-based games.