OpenArena is a community-produced deathmatch FPS based on GPL idTech3 technology. There are many game types supported including Free For All, Capture The Flag, Domination, Overload, Harvester, and more. There are 17 unique player models to choose from and 12 weapons.
A mirroring of q3dm6ish with a new visual theme, lots of fixes, and a new, more appropriate weapon/item balancing (for CTF). It's inspired by Slainchild's CTF-UCMP2-Campgrounds for UT2004.