Dishonored is 2012's Bioshock, plain and simple.
I don't mean that Dishonored apes Bioshock's style and gameplay, although I wouldn't be surprised if there was some direct inspiration involved since Arkane did work on Bioshock 2, but I mean that is a unique, polished, finely-crafted gaming experience the likes of which is few and far between. One review mentioned that the game took about six hours to beat and you can certainly blow through levels if you like, carving people up or shooting them in the face, but you can also take your time and explore every corner of each area.
Each area is dense and complex, with lots of buildings and secret areas to explore for helpful items, upgrades, stat-boosting charms, and skill-boosting runes. It's also very vertical, letting you climb high above the city streets in search of alternate paths. And you aren't just put into an area and told to go from point A to point B while avoiding a few guards, each area also has non-hostile NPCs that might give you quests are even sell you items with the money you pick up along the way.
You also come across little stories through exploration and reading books [there are a lot of books and journals and notes], stories that don't necessarily come with quests or rewards but simply add a dash of realism to a wholly made up world.
Stealth powers are one of the high points, adding an array of abilities to make being stealthy fun. One powers lets you instantly jump from one location to another. Another power shows all nearby enemies and in what direction they happen to be looking. Another power unleashes a swarm of rats that attack and consume whatever is in their path [including armed guards]. Another power lets you take control of animals and even people.
But the game doesn't force stealth on you. You won't lose a mission because someone saw you and you're not defenseless. The game gives you a crossbow, a pistol, and a sword, all of which are upgradeable. Killing every guard in site isn't without consequences though, as the fresh corpses add to the rise in rat populations and the spread of the deadly plague that's ravaging your city.
The main story is simple: a tale of vengeance against the traitors who had you unjustly thrown into prison. It doesn't try to be bigger or more important than it is, but rather takes this simple story and gives it life and details along the way. Or you can skip all that and get straight to the stealthing.
I've played over four hours and I've barely even made any progress in the first real mission.
