Nexuiz
This FPS is developed by Alientrap Software(funny name, isn't it). It uses a heavily modified Quake engine called DarkPlaces. This game have teleporters so you can jump into it to avoid being shot at, and don't worry, the bullets aren't gonna pass through the wall. This game has both single player and multiplayer option, so you can play with bots if you have a not-so-fast internet connection.
Shotguns, plasma rifle, rocket launcher are but a few of the available weapons, though my preferred weapon is a fast rapid fire missile launcher. The graphics of the game can bring your graphic card to the knees if you don't have enough graphic power. Take my AMD/ATI Radeon HD 3850 for example, highest quality without 4X AA makes my fps hover around 30~40.
Warsow
If your graphic card is not one of the high end, don't fret. There is a still a fps that provide a good gaming experience with a small system requirement. I introduce Warsow, a multiplayer only fps that looks a bit like Team Fortress 2 rip-off. The graphics looks a bit like TF 2 too as it employ the cel-shading technology to beautify the game. Even a GMA 950 used by netbooks can play this game around 30 fps in low quality.
Like the game above, there are around 7 weapons for you to pawn your enemy, which includes the rocket launcher, electric rifle, disc bomb. The special feature of this game is the ability to bunnyjump, which means that you will move faster as you jump and jump upon touching the ground. Those who played Cs 1.0 before would sure know this move.
Any more free games out there? Played these 2 games before? Please kindly leave your comments here :)