Dwarf Fortress - colony sim CDDA - rougelike FreeDoom - Doom port, compatible with most mods Lugaru - ninja rabbit fighting Minetest - minecraft clone Super Tux Kart - racing game Daggerfall Unity - rpg Pathos - nethack clone rougelike Endless Sky - space sim Hedgewars - worms like game with hedgehogs Battle for Wesnoth - strategy ColoBot - programming puzzle game/rts OpenTTD - transport tycoon Shattered Pixel Dungeon - rougelike Mindustry - like factorio but more tower defense 0.A.D - rts

these are the ones i’ve tried

oh and keep an eye out for Kitten Space Agency