FPS

First person shooter

Warsow

Warsow is a fast paced, free, first person shooter aimed solely at competitive play. It's currently still considered "in beta" as it's being updated based on community input, play-testers. While not having quite the popularity of other FPS deathmatch games like Quake3 or UT2k4, it has quite a following in the United States and most of Europe, and just had it's first cash-prize LAN event, CDC3.

Star Wars: Battlefront II

Battlefront II is the second title in the Battlefront series from Pandemic and LucasArts. The series places the player in the middle of large-scale battles on both land and space. The game is fundamentally similar to its predecessor, albeit with the addition of new gameplay mechanics. The general objective in most missions is to eliminate the enemy faction.
Like Star Wars Battlefront, the game is split into two eras, the Galactic Civil War and the Clone Wars. Players have the ability to choose between six classes during gameplay.

Crysis

Crysis is based in a fictional future, where an alien race has invaded Earth. The single player campaign has the player assume the role of Jake Dunn. Dunn is a United States Delta Force operative, who is armed with various futuristic weapons and equipment, most notably a "Nano Muscle Suit", which is an artificial and technologically advanced exoskeleton, inspired by the United States' Future Warrior 2020 program, according to Bernd Diemer, one of Crytek's senior game designers.

Half-Life: Source

Winner of over 50 Game of the Year awards, Half-Life set new standards for action games when it was released in 1998. Half-Life: Source is a digitally remastered version of the critically acclaimed and best selling PC game, enhanced via Source technology to include physics simulation, enhanced effects, and more.

Clive Barker's Jericho

Clive Barker's Jericho is a supernatural horror-themed FPS computer game with horror author Clive Barker providing the premise for the game.

Game players assume the role of the leader of the Jericho Squad – a seven man Special Forces strike team that protects U.S. interests against paranormal threats. Each member of the squad is an expert in modern warfare as well as their own different para-psychological disciplines, including clairvoyance, alchemy, blood magic, exorcism, etc.

Half-Life 2: Episode Two

Half-Life 2: Episode 2 is the latest continuation of the Half-Life story from your friends at Valve. Gameplay is essentially the same as the previous two games with the emphasis on action. There are some large maps which give a nonlinear tint to parts of the game. A new ammunition is available for the gravity gun which allows placement of Strider destroying "sticky bombs".

If you got the first two you know you are getting this one so why fight it?

Shadow Ops: Red Mercury

Shadow Ops: Red Mercury is a 2004 FPS that is available on the Xbox and Microsoft Windows platforms. You play as Captain Frank Hayden, an elite Delta Force operative. The first mission opens with Frank and other Delta Force operatives attempting to secure a briefcase nuclear bomb code named "Red Mercury" now in the possession of a terrorist known as Vlady the Vicious who is using a coast Syrian town as a base of operations.

Upon arriving in the town, the mission goes down hill when the Sea Hawk that inserted the team is shot down moments after inserting Frank and his team.

Quake

Quake is an FPS from iD Software. You play as a grunt who must travel to a variety of worlds through interdimensional portals and destroy a Lovecraftian horror and hundreds of minions before they can locate and overrun earth. Dark Places is a source port that has various enhancements over the official versions.
It may not be as impressive graphically as say, Tenebrae, but this port is the widescreen king of source ports, so it gets the honors here. Dark Places can be downloaded here (original Quake data is required and not included) http://www.icculus.org/twilight/darkplaces/

Enemy Territory: Quake Wars

Enemy Territory - QUAKE Wars is a team based FPS from ID Software.Game play is similar to Battlefield 2142.This game also has G15 Keyboard support.

Ghost Recon Advanced Warfighter 2 (GRAW 2)

Tom Clancy's Ghost Recon Advanced Warfighter 2 (GRAW 2) is the sequel to Tom Clancy's Ghost Recon Advanced Warfighter. It expands on the game play of Ghost Recon Advanced Warfighter and is the fourth installment in the popular Ghost Recon tactical shooter video game series, published by Ubisoft.