OpenArena is a Free Software FPS game licensed under the GNU GPL. It aims to recreate the data used by the GPL Q3 source from scratch. It plays identically to Quake III: Arena, however it does not require it to run. It is entirely Free and stand-alone. The engine used is ioquake3 for security fixes and feature enhancements.

The game is available and compiles for Windows (95 and up), GNU/Linux and Mac OS X.