Spec Op: The Line. With a name like that and a setting like that, I thought it was going to be another bang bang wankerfest. I only bought it because the gameplay looked like fun. It actually wasn't that great, but the game has one of the best stories in recent gaming. Jesus Christ, man. If you haven't played this game, I very strongly recommend it.

Morrowind is worth a shout too. I went in expecting it to be a good game, but that I'd have a little difficulty with the clunkiness. It's so much better than I thought it would be. I remember trying it on the Xbox and thinking it was trout, but the PC makes it much easier to swallow.