Top 5 FPS ever played?

[IllegalPaladin]

I've certainly enjoyed numerous FPS games, but I'd say that games pumped out by Valve are usually some of the better ones I've played.

Half-Life
Half-Life 2 (and episodes)
Team Fortress Classic and TF2
Counter-Strike (1.6, CZ, and Source)

I'd have to say that these are some of my favorite games that still get playtime to this day. I never really got into Day of Defeat, but I do play Day of Defeat: Source from time to time.

There are other ones which are good too,

The Battlefield series (I own and still play BF2 from time to time, it can be good even though it has a lot of issues).
Bioshock - It was good even if I didn't like the level progression (oops, this area is now blocked..... go around and do a bunch of crap to unblock it)
Call of Duty 4 - Short and very linear, but it had some cool moments that are fun to replay.