CodeRED: Alien Arena is a free and open source retro sci-fi FPS multiplayer game. Alien Arena is an old school death match FPS game with modern features, combining aspects from games like: Quake III Arena & Unreal Tournament, giving it a fast-paced and intense gameplay. The game is heavily multiplayer based, however single player mode is available allowing you to use bots. Alien Arena is a very light game which requires very minimal hardware to run, this means it will run on almost any Mac.
Intel powered Mac
OpenGL 2.0 compliant graphics card