OT: Best 1st-person shooter game?

[cmsanto]

Best 1st person shooter game experience ever for me was Half-Life.
Truly a great game.

Medal of Honor was near great but I got stuck in the village mission, so I never completed it. For on-line play though, Medal of Honor, and the various mission packs are exceptional.

If you want something a little different. System Shock Two was a ton of fun. Creepy as all hell. Game can be played in many different ways and especially as a 1st person shooter.