Alien Arena: Mercury Edition(7.65) for Linux/Unix/OSX

Do you like old school deathmatch with modern features? How about rich, colorful, arcadelike atmospheres? How about...retro Sci Fi? Then you're going to love what Alien Arena has in store for you! This game combines some of the very best aspects of such games as Quake III and Unreal Tournament and wraps them up with a retro alien theme, while adding tons of original ideas to make the game quite unique.

Built for fraggers by fraggers.
Alien Arena is a furious frag fest with arenas ranging from the small, to the massive. With a large built-in player base, it's never hard to find a good match going on, at any hour of the day. The community is friendly, as well as prolific. Dozens of maps, models, and various accessories have been created by community members to add on to the game experience.

Open sourced. Ever Evolving.
The CRX engine that powers Alien Arena has received very signifigant upgrades in recent releases, resulting not only in stunning new visuals, but vastly increased performance as well.

http://red.planetarena.org/