Seriously, would anybody be talking about Half Life anymore if it wasn't for the 10^99 mods that have come out for it, amongst them such minor things as Counterstrike?
The single player for Half Life was a lot of fun, but it was freakin' linear as hell (to the point where EVERY monster appeared at EXACTLY the same spot), and there have been a plethora of games (not necessarily FPS games) that have given you a greater game experience overall (Deus Ex anyone?).
So still hailing Half Life as "the greatest game ever" is kinda absurd in my opinion, simply looking at Half Life itself.
Calling it the greatest MULTIPLAYER "base" game is probably still justified. Natural Selection is absolutely awesome
Creston