Free Games [pinned]

Free and open source games, some of which are also available on Steam (if they're also on Steam, I'll mark them with a *).

- Shooters

https://xonotic.org/ - Quake-like Arena shooter

*https://redeclipse.net/ - Another quake-like arena shooter

- Strategy

https://mindustrygame.github.io/

*https://wz2100.net/ - vehicle RTS with customizable units

*https://www.wesnoth.org/ - Turn/grid based strategy game.

http://www.openra.net/ - FOSS reimplimentation of RedAlert

http://www.freeciv.org/ - Turn based Grand Strategy

https://github.com/yairm210/UnCiv - "

https://play0ad.com/ - unit/civ based RTS 

https://zero-k.info/

https://www.freeorion.org/ - Space based grand strategy/4X

- Platformers

https://www.srb2.org/ - 2.5D Sonic the Hedgehog game

http://www.cavestory.org/ - Side scrolling platformer/shmup (Note: The Steam version is not free, it was basically stolen from the OG dev)

https://www.supertux.org/ - 2d platformer

- Racing

https://supertuxkart.net/Main_Page

https://sourceforge.net/projects/torcs/

- RPGs

https://www.themanaworld.org/ - FOSS MMORPG

http://www.cataclysmdda.org/ - Turn based survival game

https://sulisgame.com/

https://oolite.space/ - Custom FOSS build of ELITE

https://pioneerspacesim.net/ - Space adventure and exploration

http://www.freedroid.org/ - iso-rpg

*https://naev.org/ - Space sim

*https://endless-sky.github.io/ - Space sim (Like Escape Velocity, if you remember that)

- Misc

https://www.luanti.org/ - Voxel game engine, but you can install games from within it, including Minetest and VoxelLibre

https://veloren.net/ - Voxel adventure/dungeon crawler

https://www.openttd.org/ - FOSS Transport Tycoon