I've spent the majority of my first play-through of Dishonored as a kind of vengeful rat herder - the Pied Piper of Fuck You, here to ruin everyone's day with my swarm of flesh-eating rodents.
In case the gushing reviews haven't tipped you off, the game is brilliant. It's a masterpiece of design thievery, liberally bogarting ideas from a host of games. There's very few original ideas on show - in fact I couldn't find a single skill or mechanic that hasn't been pulled from some other game - but there's something to be said for just taking what works and mashing it together.
Unless something comes out of left field in the winter months, I'd say Dishonored is easily the best AAA game of this year. Though funnily enough, while it's the best overall package, it's not the best stealth game. That honor goes to Klei's Mark of the Ninja, which actually shares a lot of its mechanics with Dishonored, but offers a far more focused experience. Dishonored really doesn't give the player much of a reason to approach, never mind kill or subdue, its various guards, which is odd since it rewards pretty much everything else you do. Corvo is so mobile (and quicksaving so tempting) that you'll rarely, if ever, have to do any actual sneaking. Mark of the Ninja, on the other hand, rewards you getting up close and personal with the guards: Sneaking past them nets you points, terrifying them with dead bodies does too, as does killing them or tricking them into killing each other. Both games scratch my stealth itch in different ways, despite their occasionally similar mechanics. Dishonored is a playground: Open, fun, lacking in structure. Mark of the Ninja is an assault course.