Alien Arena is a fast paced, 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.
Alien Arena has running tournaments and you can organize your own at TournamentFront
Current tournament is Qexpo 2008 Aliens For Animals 1v1 Tourney.