Alien Arena 2008 is a free standalone deathmatch game based on source code
released by id Software. Begun by COR Entertainment in 2004, the game combines
a 1950s-era sci-fi atmosphere with gameplay similar to the Quake, Doom, and
Unreal Tournament series. Alien Arena focuses mainly on online multiplayer
action, although it does contain single player campaigns against bots.

Alien Arena has been released for Microsoft Windows, Linux and FreeBSD. Alien
Arena has been free-to-play since its inception, and there are currently no
plans to change it to pay-to-play.