As per the title.

Mine is the Half-life series and the mods that you can use. Just because when the game first came out it challenged everything about the FPS genre. Its older now but you ask most gamers they will know what i am talking about.

there isant one best, there all rubbish

After reading your subject line I stated to think... My first reaction was to think of Half Life. If we are to include all of the Valve games to have come from HL then it has to be up there with the very best.

For single player Call of Duty must get a big mention, the cinematic story line. If you think it's a cheat or a stroke of genius to have you play through the best bits from well known war movies. If you love war movies then you will love Call of Duty, you get to take part...

We also have to mention some other great single player games like Farcry, Project IGI and a game series I have put a lot of time into Medial of Honor.

As for Multiplayer then the simplicity of counter strike, DoD or MoH. How about the total fragfest that is Quake?

I like my fps games to be a little more tactical so I like the big map games like Battlefield series and Novagames titles like Joint Opps the latest in the Delta Force family.

Jedi Knight imho

DOOM 1/2.

Over ten years later and I still play it ALL THE TIME.

It is a hard call. Several games in the FPS genre has given me a phenomenal gaming experience.
Doom had it going because of the emergence. Play it with stereo sound, and it was just scaring!
Dark forces had the whole starwars theme going.
Rise of the Triad (rott) was quite fun, but never "the greatest experience ever."
Duke Nuke'em 3d just a classic. Great one-liners, Schwarzenegger in a game
Shadow-Warrior, also by 3Drealms, even better. This time you have the Nuke.
Jedi Knight is also a great game. Really one of the first games that used a consistent story-line. Great in multi-player too.
Half-Life the first one with all the story taking place inside the game engine. Great idea.
And let us not forget GoldenEye64. First game with independent body parts. Shoot your enemy in the head and he dies.
The entire Quake series, as well as Unreal Tournament, enhancing on-line gaming.
Doom 3 and the expansion seems to be my favorite at the time. I just admire the way ID manages to get the effects across on the screen. Just amazing.

Although Doom1 & 2 multiplayer is amazing... I'm going to have to go with Halo2.

The Xbox LIVE aspect of Halo2 is just a hands down winner in my opinion. If you've never tried it with the headsets and decent no-lag connections then you need to! (In about a 1000 games I can only remember about 4 or 5 which lagged.)

Serious Sam......great game.

sorry i meant to be a little more specific, i am more of a PC gamer, there are many FPS out there for all of the different consoles, But by all means we can include those :-)

With those included.......lets see...
(puts on his thinking cap)
Ill get back to that one

I think the best FPS of all time for me (maybe not anymore, but it was the highest played game ive ever had), would have to be Goldeneye for the N64.

I still love that game to death.

Yeah that was a damn good game, and Perfect dark, which seems like it was made because of Goldeneye, i dont remember which came first or if they came out about the same time....*hint *hint

Half-Life, with Doom being a close runner up.

there isant one best, there all rubbish, and boring, and pointless......

Gioldeneye64 came out first as one of the release games on the N64. Perfect Dark came out in the N64's dying days.

Alright, alright. Point noted. You despise FPS'.

I second that! I loved Goldeneye 007 for the N64

The coolest thing about Goldeneye64, besides the independent body parts, must have to be the two-controller control system

That feature actually made the control system good. And is the only time I have felt comfortable by playing FPS on a console. Other control systems devised this far on consoles, just does not work!

But the Goldeneye64 two-controller control system did work!

Rise of the Triad, IMO.

Goldeneye would be my second choice.

Gears of War and Halo 2 both single player & multiplayer.

After trying out Goldeneye 64 at a friends house, its two player control is a blast. Goldeneye is a real gem

Half-Life and following games.

The story rocks, the modability gives it longevity, the mods are awesome, the multiplay is a blast. I love it to death.