All the 3D linux gamers out there...here is a collection of all time best free 3D linux games. Some of which have won awards. Sorry if i had missed any of your favourites. Share your favourites in the comment section.
America's Army

America’s Army is a tactical,multiplayer,FPS (first person shooter) owned by the United States Government and released as a global public relations initiative to help with U.S. Army recruitment. The first version, Recon, was released on 4th July 2002. The current version 2.8.2 was released on september 2007.
It’s the first well known computer game used for political aims. The game is used as a playable recruiting tool and critics have charged the game serves as a propaganda device. A counter on the homepage of the PC version shows over eight million registered accounts as of 2007. GameSpy tracked the game usage and reported an average of 4,500 players at any one time between 2002 and 2005.
Tremulous

Tremulous is an open source team-based FPS (first person shooter) with a game play that is similar to Gloom (a Quake 2 mod) and Natural Selection (a Half-Life mod). The game features two teams, humans and aliens, each with their own strengths and weaknesses. The game has been downloaded over 200,000 times and was voted “Player’s Choice Standalone Game of the Year” in Mod Database’s “Mod of the Year” 2006 competition.
Tux Racer

Tux Racer is a newbie friendly, open source, 3D computer game starring the Linux mascot, Tux the penguin. Like many open source games, the replay value of Tux Racer is extended by easy modification of the game. New maps can be created by making three raster images to indicate height, surface, and object placement. The last release of Tux Racer was version 0.61, 29th October 2001.
Nexuiz

Nexuiz is a free, cross platform, FPS (first person shooter) distributed under GNU General Public License by Alientrap Software. It started back in May 31 2005 with version 1.0 using DarkPlaces, a significanlty modified Quake engine. The current version, 2.3, was released on May 31, 2007. Available for Linux, Mac and Windows.
Alien Arena 2007

Alien Arena is a completely free FPS (first person shooter) started by COR Entertainment in 2004 comprising of a science fiction ambience and a Quake like gameplay. This game is playable in single player mode against bots, but the action and thrill lies at the online multiplayer mode. Features of the Alien Arena 2007 include an internal server browser for finding other people to play online and an external program that acts as an IRC interface. There are 6 game types and 6 game mutators that changes the gameplay. Cattle Prod is a new game type that requires you to herd robotic cattle to earn points. Alien Arena 2007 is playable in Linux, Windows and FreeBSD.
TC:Elite
TC:Elite happens to be a total-conversion modification of Wolfenstein: Enemy Territory by Team Terminator and Groove Six Studios. The game is free and playable across all platforms. Notable features include iron sights aiming (no crosshair), multi layer object penetration, letterbox / wide screen view modes, lag compensation, client side bullet prediction and support for PunkBuster, the anti cheat software.
TORCS
TORCS is an open source 3D racing simulator using OpenGL technologies. It is runnable on all Linux, FreeBSD, MacOSX and Windows platforms. There are 50 different cars, 20 tracks and 50 opponents to race against. The multiplayer mode can accommodate up to 4 human players. Several of the simulation include damaged models, collisions and aerodynamics like ground effects, spoilers, etc. Development is currently being carried out to enable online racing mode.