According to the game's co-creative directors Harvey Smith and Raphael Colantonio, Dishonored could take players up to 28 hours to complete.
"Play-style matters a lot. Very direct players will probably get through the game in 12 or 14 hours. Explorers who eavesdrop a lot will take twice as long,"the pair answered on the Bethesda Blog.
"There are six major active powers and four enhancements (passive powers), in addition to weapons and gadgets; plus there are 40 bone charms in the game that grant small supernatural perks. But no one can have all of these things in one playthrough."
Dishonored is set for release on Xbox 360, PlayStation 3 and PC on 12th October.