Update: Regarding the question about how long Dishonored will be, co-creative director Harvey Smith added the following in a tweet today:
Regarding play-time in #Dishonored: Very direct players finish in ~12 hours and explorers who eavesdrop finish in ~24.
Over the last week, we’ve collected your Dishonored questions both here on the blog and on our Facebook pages. To answer the first batch of questions we have co-creative directors, Harvey Smith and Raphael Colantonio.
Q: How does mana work in Dishonored?
A: A small portion of the mana bar regens; just enough to use powers like Blink and Dark Vision, making them basically free. Beyond that, for the expensive powers like Possession or Bend Time, the player must rely on Piero’s Spiritual Remedy (mana potions).
Q: How many different powers will there be?
A: 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.
Q: How long will the game be?
A: 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.
Thanks for the great questions. If there’s something you’d like to know about Dishonored, post your question here on the blog or at https://facebook.com/dishonored