@rain Supertuxkart, minetest, xmoto, hedgewars, powermanaga, tecnoballz, supertux2, extreme tux racer, ultimate stunts, vdrift, speed-dreams-2, GNUjump, GNU liquid war, Xonotic (offline), mars-game, xbill (and xlennart variant), orbital eunuchs sniper, the games in Emacs (tetris and snake are the best), Emilia pinball, gltron, I have no tomatoes, taisei and many more I can't remember right now.

All fine games and all freedom respecting.