Dishonored looks to be a mash-up between BioShock, Hitman, Deux Ex and Thief. Harvey Smith, one of the original developers of the first Deus Ex game is the lead developer of Dishonored, so this should not be a surprise. Dishonored is an FPS comprised of a set of linear missions, but you can choose to complete them however you want: stealth, all guns blazing, persuasion, divide and conquer; whatever floats your particular boat.
The game is set in an original steampunk world, and sees you play as Corvo, bodyguard to the Empress who winds up dead with you being framed for her murder. As your head nears the chopping block you are rescued and freed by persons unknown who also imbue you with supernatural powers, such as the ability to slow down time (stop me if you've heard this one before), teleport or even possess people or animals for a brief time. How you choose to complete each mission is up to you, so multiple playthroughs to test out various scenarios would seem to be the order of the day, with the ultimate aim of clearing your name and exposing those behind the conspiracy.
The developer is Arkane Studios, a Zenimax-owned studio based in France but with a US presence in Austin, Texas. Their previous works include Arx Fatalis, an open-world RPG released a decade ago, and they were also one of the myriad of developers who worked on BioShock 2, specifically in design, artwork and animation. While their pedigree is not tremendously strong, they were aquired by ZeniMax in 2010 and another ZeniMax company that we are all familiar with, Bethesda, will be publishing the title.
There is not a tremendous amount of information out there about the gameplay, which is somewhat surprising considering the release date is slated for October of this year, but it could well be that they are planning a big push from E3 and beyond in the run-up to launch. With BioShock Infinite being pushed back until February of 2013 then there would seem to be a gap in the market for a solid single-player, multi-platform title like Dishonored.
Be sure to check out the teaser trailer linked at the end of this post, and keep your eyes glued for more Dishonored information since this could be something very impressive if all goes according to plan.