Bethesda recently announced the existence of Dishonored. It's being co-created by the man behind Deus Ex and Thief, Harvey Smith, with a visual style from Half Life 2 artist Viktor Antonov. GameInformer have the first details and a screenshot.
Dishonored is about assassination. You play as Corvo, legendary bodyguard to an Empress. Gadgets, supernatural abilities, skill with weapons and stealth makes you an exceptional killer, but it's up to you to choose the means by which you dispatch your targets. A 'chaos' system will measure your approach, recording the amount of carnage and collateral damage you cause as you carve a path through the steampunk world. GameInformer call the chaos system a "behind-the-scenes element that affects story decisions without punishing the player or pushing them to play one way or another."
You begin the game in prison, accused of the murder of the Empress you were charged with guarding. The corrupt Lord Regent has framed you as the guilty man, but severely underestimates your abilities. Gadgets and special abilities will let you freeze time and possess creatures. These can be combined to give you a wealth of options with which to take on your target.
"You can combine them organically to create interesting effects," write GameInformer. "Stop time and knock a bunch of stuff off a table in one direction then book it in another, so the guards search for you in the wrong place. Summon a swarm of rats to attack one guard, but possess one of the rats and escape in the chaos. Every problem has as many solutions as you want it to."
GameInformer's screenshot shows the player locked in combat with a man wielding a sabre and a flintlock pistol. Arkane previously made Dark Messiah of Might and Magic, best known for its excellent first person combat rife with devastating mace blows and environmental hazards that could be turned to your advantage.
We'll have to wait and see whether Dishonored will have a similar combat system, but the recipe of combat, stealth, gadgets and superpowers suggests that the game's shooting for a level of player choice that made Deus Ex and Thief great. We'll know more as Bethesda reveal their secrets, unless we can discover them first. We've got our best possessed rat on the case.