Unreal Tournament

Unreal Tournament is one of the best first-person shooter games ever made. It has awsome 3D graphics and unmached gameplay. UT is a followup to the popular Unreal game. Unlike Unreal, it is not a "mission" game so to speak. Instead it is split up into four game categories;

Assult Mode - You first attack and then defend! You get a list of objectives that you must complete within a certain period of time such as destroying a gun or escape a castle. After you have completed these objective, you must stop the other team from doing the same in a lower amount of time!
Domination - You compete against the other team to secure "control points", a real test of teamwork!
CTF - Capture the flag, self explanetory, you raid the other teams base and steal their flag, then get it back to your base... while stopping the other team from doing the same!
Deathmatch - Gettin' back to the basics....kill the enemy!!! The ulitimate test of your killing abilities!

It also has internet muliplayer mode which is truly awesome, you can play all the modes with your friends!

My favourite UT webpages:

http://www.planetunreal.com/
http://www.unrealtournament.com/
http://www.unreality.org/
http://www.utcenter.com/