I got bored of Bioshock about halfway through, never got round to completing it. I was also very tempted by Prey, but went for the Unreal deal instead - haven't played UT 2004 or UT3, and I remember the single player games being a great deal of fun, so more stuff added to my pile of games to play when the deals stop rolling in. Space Siege is definitely worth a pop if anyone's sitting on the fence, sorta like an updated Crusader (god, I miss those games) in diablo-style action RPG, quite simple and not huge but better than the 60% metascore it's got.