Nexuiz v1.0, an fast paced deathmatch FPS, has been released under the GPL. It uses a heavily modified version of the Quake 1 engine, with real time lighting/shadowing, improved particle effects and more. It looks really good and it's available for Windows and Linux, with a Mac version said to be coming soon."
http://www.nexuiz.com/
http://www.icculus.org/twilight/darkplaces/
PS: Vous avez essaye ?