All of these are games I've put countless of hours into. There's a bunch of other good games, SuperTux, Pingus, Tux Racer, Neverball/neverputt, Armagetron Advanced, Minetest, 0ad, some of the KDE games, and more that I've played and liked but haven't lost nearly as much time with.
Teeworlds, Fast-paced 2D shooter that has had an undying community for ages. https://teeworlds.com/
Stepmania, DDR-like rhythm game. You know the drill. Also consider the Etterna fork if you're a keyboard fanatic. https://www.stepmania.com/
Shattered Pixel Dungeon (Android), a very good roguelike to fill the void when you only have a phone nearby. http://shatteredpixel.com/
NXengine (or nxengine-evo), an open source engine that can be used to play cave story. Apart from some minor bugs a really good way to experience the game. https://nxengine.sourceforge.io/ https://github.com/nxengine/nxengine-evo
All of these are games I've put countless of hours into. There's a bunch of other good games, SuperTux, Pingus, Tux Racer, Neverball/neverputt, Armagetron Advanced, Minetest, 0ad, some of the KDE games, and more that I've played and liked but haven't lost nearly as much time with.