Bioshock

I love killing monsters as much as the next monster killer, but often First Person Shooter games tend to tire me out pretty quickly, and have little, if any, replay value. Bioshock is a whole new deal. Not only is the shooting aspect of the game extremely well made (everything from a wrench to Napalm ejecting rockets are at your disposal) the player can also genetically modify his body to control gravity, spray fire, bugs, electricity and do all sorts of other twisted shit. But the game really shines in it's Art Nouveau design (that is beautifully rendered and lit), disturbing sound environments, and story line that reads like a Ayn Rand novel on peyote. Fun!