Far Cry 2. There's so much hate for this one, but I still think it is a brilliant and very engrossing game. If you are dismayed by "respawning enemies", then you are just playing it wrong, admit it!
Furthermore, remember that the PC version has save-anywhere, so
USE IT, if you really dislike having to drive all the way to the mission objective again when failing the mission. Don't complain for nothing, just use the fecking save anywhere! It solves that "problem". If you are playing the console version instead without save-anywhere... well boohoo! Serves you right for playing it on a console!
Frankly, the only real complaint I have about FC2 is that it doesn't have good music, like the first Far Cry had, or e.g. Crysis 2 has.
Another might be
<span class="bold">Area-51</span>. It is a generic futuristic military FPS, but I still enjoyed it overall. It was somewhat like a poor man's Halo. What is has, and Halo doesn't, is that you can occasionally turn into a big scary alien monster! (due to some alien virus or something you have, I don't recall anymore)
And while we are at it, I think the PC versions of all these were good:
Halo
Halo 2
GTA 3
GTA: Vice City
GTA: San Andreas
People who complain about the PC versions being rubbish are rubbish themselves. It doesn't make you look cool to claim these were inferior to the console versions. The PC versions are fine (and the controls on all these are faaaar superior to the console versions, a fact!), the problem must be in your brains.
Had enough? No? Then go to your mama for some more!