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.
Nice Q3-based shooter, but I just like original Q3 much more, although, in modern days Q3 lacks some features and game modes, found in OA. Although, there's Quake Live, but completely stand-alone game is much better than game dependent from browser.