Oh my cack, y'all are missing out for having not bought the first two Thief games during this sale. Stuff like BioShock gets too much praise by comparison when it comes to immersive ways to tell a story in a first-person game, in my opinion. Even though it's the same scenario writer, I feel that Ken Levine shouldn't have strayed from the conventions set up by the other Looking Glass Studios developers for Thief; he copied DOOM 3 instead, which is unfortunate.
The only trouble with the first two games (or maybe it's just the first, I can't remember) is that playing on the hardest difficulty, you can't kill any guards, and sometimes ya REALLY just wanna off one or two of 'em! Especially if you're spotted, because your only options are to run away and hide or reload. I want some sword fights, dammit!
Reason I play on the hardest setting is you're given more fun mission objectives which are really satisfying to fulfill.