OpenArena is an Open Source re-packaging of the Quake Arena III FPS game. Proof once again that free software can be fun too, y’know. 

 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. Bots were added starting in 0.6.0. They will spout taunts and everything! Concepts would be loose, so don’t expect a remake of Klesk in his original Klesk form, or any direct remakes of any map/weapon/model.