Looking awesome. Can't wait. I hope they market this as much as it will need though. This'l be a fairly narrow audience for those who know what to expect and are looking for this kinda game. People are becoming less willing to pay out for less 'mainstream' gameplay.
^ Then casuals can stick to their annual Madden and Call of Duty games and core gamers can still have a place with games like Dishonored. Harvey Smith and Raf Calantonio are developers of yersteryear, so I trust them to bring something unique to the table.
It's all well and good being a staunch 'elitist' or whatever but without a decent amount of people to buy the game these kinda games will fall by the wayside, and less developers will be wanting to make them and less publishers will want to publish them. Hence why we have so few of these kinda games. Deus Ex being the last one I can remember, the one before that... Alpha Protocol?
I'm personally looking forward to the world they've crafted. Too many games these days put you in the boots of some soldier fighting in whatever modern/near future war... It gets dull. Where as games like Mass Effect, Bioshock, Skyrim, all create these places we'll never see.
Of course the gameplay sounds awesome too. I'm not sure how well stealth and first person will work together, but over all I'm really happy with the fictional elements like teleportation and controling rats... Should make it feel even more unique.
If you want a game that does stealth and FPS look into the original Deus Ex.
I'm hoping it'l be along these lines. Keeping out of eyesites and keeping to shadows. If its gameplay is something like Deus Ex, with a hub world with areas off this to be explored and missions to be done in, along with upgradable abilities ( and maybe weapons ) this game will be a first day buy for sure.
Steampunk is something that is very hit and miss for me. Some goes way over the top, too much towards fantasy and magic imo. Whilst others try and be realistic which is probably worse. This however seems to be a decent balance, and I'm highly intrigued.
If anyones into steampunk I'd look up a comic called 'Lady Mechanika'. It's awesome.