Recommend Me A Good First Person Shooter.

BulletStorm - great campaign, lovely humor ;)

Crysis 2 - Really good game. Not phenomal but totally worth your money. Multiplayer is also something different among all those CoDs and BFs.

Battlefield 3 - another solid shooter if You like multiplayer. Don't bother with single in it, tho.

Team Fortress 2 - tons of fun ;)

Quake 4

CS 1.6

Blood (One Unit Whole Blood) is awesome.

Payday

Serious sam franchise

COD 4 or CSS

Call of Duty

Offline - Borderlands i played it for years and cant stop doing it, because its fun and complete if u can buy or ""buy"" the dlc's
Online - Borderlands or 1 of the Counter Strike games.

Half-Life & Half-Life 2. The best!

Half-Life series
Doom 3
Quake 4
Call of Duty 1-4
Prey
Medal of Honor: Allied Assault, Pacific Assault
Battlefield 2, 3, BC2
Borderlands
Alien versus Predator 1-2 (not the newest)

Star Wars Battlefront 2 On the Playstation Two, because then it doesnt have bugged out Graphics
EDIT: Its also an Third person shooter, You can decide by pressing an button or going to game options

IRL with gun DLC.

Return to Castle Wolfenstein, Undying..

Battlefield 3 IMO, also ARMA if you like simulation...

Are you looking for single player or multiplayer FPS?

Reallife 2012 with Norway DLC.

Alien vs Predator 2

lol, i'll go hipster on this one (a little bit) :)

Try Shadow Warrior. A 1997 game with LOTS of gore. And I mean "LOTS".

And that's a shame that noone said Duke Nukem 3D, which you should already played it sometime. If not; don't bother reading this topic. (:

Brothers In Arms is a good franchise.

I can recommend Call of Cthulhu: Dark Corners of the Earth but it has an incredible amount of bugs (ding! Bethesda!!). Be very patient on this one. (:

The Darkness is good. You can try it. (:

The first F.E.A.R. without the expansions. You won't believe how bad they could be... (F.E.A.R. 2 : Project Origin is good but the first one is the best. Never play the 3rd one.)

NEVER play Legendary. Don't even consider it. It's that bad.

Also you can try; Metro 2033,Undying, MoH serie, Dreamkiller, Painkiller, Prey, Wolfenstein, Doom, Quake, RAGE, Red Faction serie, Red Orchestra serie, QUBE, Stalker serie, Serious Sam serie, SiN, UT series... The list goes on like forever... (:

PS: Some of the games listed here are "so bad that it's actually good". :)

MW3, haha just kidding