OpenArena is an open-source content package for Quake III Arena licensed under the GPL, effectively creating a free stand-alone game. You do not need Quake III Arena to play this game. The latest version adds 26 new maps, 10 new player models, new announcer voice, new gibs, and more (check full article for changelog). Thanks: Andrew.

OpenArena v0.7.0 Free Full Game for Windows/Linux (250.94MB)

OpenArena v0.7.0 Free Full Game for Mac OS X (263.11MB)