Armagetron Advanced

http://www.armagetronad.net/

Armagetron is a multiplayer game in 3d that attempts to emulate and expand on

the lightcycle sequence from the movie Tron. It's an old school arcade game sl

ung into the 21st century. Highlights include a customizable playing arena, HU

D, unique graphics, and AI bots. For the more advanced player there are new ga

me modes and a wide variety of physics settings to tweak as well.

Battlestar Galactica: Beyond the Red Line

http://www.game-warden.com/forum/showthread.php?t=3502

• Powered by the revamped Freespace 2 engine

• Entirely stand-alone, Freespace 2 not required

• Accurately detailed high-resolution ship models

• High quality, originally engineered audio

• Authentic, original in-game soundtrack, in addition to pieces by Bear McCreary and Richard Gibbs

• Original characters and voice acting

• A three mission single player campaign depicting never-before-seen eve

nts, interwoven with and true to the series’ storyline

• Head online and go head-to-head with your friends—and foes—in intens

e multiplayer missions including Deathmatch, Capture the Flag, and others

• Exciting Viper combat with authentic weaponry and flight controls

BZFlag

http://bzflag.org/

BZFlag is a free online multiplayer cross-platform open source 3D tank battle

game. The name originates from "Battle Zone capture the Flag". It runs on Irix

, Linux, BSD, Windows, Mac OS X, and many other platforms. It's one of the mos

t popular open source games ever on Silicon Graphics machines and continues to

 be developed and improved to this day.

Cube 2 "Sauerbraten"

http://sauerbraten.org/

Free single and multiplayer first person shooter game with some satisfying fas

t oldskool gameplay. A large variety of gameplay modes from classic SP to fast

 1 on 1 MP and objective based teamplay, with a great variety of original maps

 to play on.

Level editing has never been so much fun: a press of a key allows you to modif

y the geometry / textures / entities in-game, on the fly. Even more novel, you

 can make maps together with others online, in the unique "coop edit" mode.