Nexuiz

Description
Nexuiz is an open source 3D multiplayer shooter, licensed under the GPL, and has been in development for over 3 years. The developers' aim was to create the ultimate deathmatch game, by bringing the gameplay back to the basics with perfect weapon-balancing and fast-paced movement. The DarkPlaces engine is used, an advanced Quake1 engine with realtime lighting and shadowing, new particle effects and Md3/Md2 model support.
The freedom of movement provides strafe jumps, double jumps, circle jumps, mid-air control and rocket jumps. Eight weapons have been included with secondary firemodes that allow for advanced tactics. There is no story, just 17 maps with different themes and 15 player models to choose from. The servers support up to 64 players and all possible settings can be tweaked in-game. The game also has an internal server browser to find online games without a hassle.