Three names and three reasons why you should be interested in Dishonored: Raf Colantonio, Harvey Smith and Viktor Antonov.

Colantonio is known for his work on Arx Fatalis and Dark Messiah of Might and Magic, Smith is famed for his contributions to Thief: Deadly Shadows and the Deus Ex series, and Antonov is the chap that designed Half Life 2's City 17. So while Dishonored might be a new IP with a stupidly spelt name (where's the 'u' dammit!?), it's got a pedigree that will likely prick up a few ears.

You play a fellow that goes by the name of Corvo. He was the bodyguard to an Empress, but then she went and got herself murdered. The powers that be think it was him that gone and done it. After doing his time, he's released back into the big wide world, and there's one thing on his mind: finding the bastard that set him up. While Corvo is a silent protagonist, it's fair to say that all that time in the slammer has changed him somewhat. Once a respectable bodyguard, Corvo is now an employee of the shadows; an assassin.

His quest for revenge unfolds in the city of Dunwall. Despite the 17th century London vibe and steam punk technologies - cobbled streets juxtaposed with steam boats and dishevelled looking robots - the environment smacks of City 17. The art style is certainly similar, but the similarities are portrayed more in tone than anything else. During an industrial revolution fuelled by the discovery of whale oil, Dunwall has seen great technological advances. Poverty is still rife, however, and there's a great sense of oppression hanging over the city. Guards litter the streets and order is enforced with a heavy hand.

What's worse, half the population has fallen victim to the plague, with rats still scuttling about the streets, spreading their vile diseases. Like the plague, the gamescom demo begins life in the sewers. Our mute hero is given a mission to assassinate a corrupt lawyer, who is scamming the denizens of Dunwall of their hard-earned coin.

As he emerges from the dank underbelly of the city, a tanker sails past along the river, a dead whale hanging from its deck. It's an impressive scene, and a great tone-setter. The whale oil is what fuels the city. One of the first portions of gameplay we see revolves around something called a Wall of Light, which - powered by whale oil - stops rodents (and other street-rats) making their way into the city. Unless you're sporting the correct key of sorts, the gate will electrocute anybody that passes through it. To get the lawyer, Corvo needs to pass through just such an obstacle. Suffice to say, he doesn't have a key.

Colantonio was keen to stress the notion of choice. "We want to give you the tools to be creative." He explained. "It's your style". To that end, the player can approach the mission in one of several ways. In terms of this Wall of Light, players could choose to hack the thing, turning the technology against the guards. This requires design blueprints, however, so was a no-go in this case. The option that played out in the demonstration saw Corvo simply yank out the whale oil fuelling the thing, allowing a horde of rats safe passage into the city.

The mission as a whole can play out in numerous ways depending on your preferred style of play. You could choose to kick up as much fuss as possible, storming through the city to the aristocrat's mansion, and killing anything that stands between you and the lawyer. Or - and for my money this is the much more interesting option - you could choose a more quiet option. Although you won't see the deliciously brutal assassinations, a stealthy approach appears to be far more satisfying.

As well as the usual sneaking about in the shadows malarkey, there are several more interesting mechanics that tie into the stealth side of the game. Rats, for example, are more than just a plot device; they're intrinsic to the very way the game plays. At one point, Corvo finds a woman being mugged by three burly men. After slicing off their heads with an expert flick of his knife, the ungrateful woman runs off screaming. This attracts the attention of nearby rodents, who engulf her in seconds. In a haze of blood and screams, she's quite literally eaten alive. This could happen to Corvo too, of course, but only in the shadows. Stay in the light if you don't want to be eaten.

Rats can do more than just eat enemies (and helpless women) alive, however; Corvo can possess the buggers, too. Indeed, Corvo isn't just a plain ol' assassin - he's a super-natural assassin. In the demo, Corvo gained entrance to the lawyer's mansion by shifting into the body of a rat. He scrabbled his way through a few tunnels under the house, and then returned to human form once safely inside. Quite what else Corvo can do in rat-form remains to be seen.

Once in the mansion, Corvo goes all out on the stealth-front. He memorises the movements of guards, planning his movements from room to room accordingly. He silently stalks guards, pick-pocketing their keys and eventually granting himself access to the lawyer's room. After peering through the key-hole and confirming that he was indeed as corrupt as his sources lead him to believe, he bursts through the door, grabs the bloke and plunges his trusty knife into his neck. After a prolonged period of calm creeping about corridors, the madness that follows the assassination is rather welcome.

It might look a little rough around the edges at this stage in development, but there were several flashes of brilliance during the twenty minute demo. The options available to Corvo at any one time are vast, and the open-world nature of the game compliments this nicely. I didn't get to see all too much of the skill system underpinning the game, but a familiar looking ability-wheel frequently graced the screen. It's an ambitious title, but if stealth and combat - the bread and butter of the experience - are of a high enough calibre to match the scope of the game, Dishonored could be one of the best new IPs of 2012.

Dishonored is due for release on Xbox 360, PlayStation 3 and PC in 2012