Quick question, is that to finish everything, or only story? Or is there nothing else other than story?
Replaying the first carmageddon, I'd say it's less than 12 hours to finish it, but I wouldn't call Carmageddon short...

For some genres, i.e. RPG, twenty hours would be short. For a stealth game, it really isn't--certainly Metal Gear Solid came nowhere near that length.

critics reviews + overhype =/= quality :p
http://www.vg247.com/2012/10/09/dishonored-too-short-youre-doing-it-wrong/

Doesn't really answer my question, but it seems to be longer than 20 hours from that (40+ it says).
Also, since we are linking youtube videos, see this one, it takes only 7 minutes to finish the game, who would pay for that game?

Length needed to finish isn't the same as time spent enjoying a game, unless I'm missing something.

I haven't read any reviews (I never do for games I haven't played yet) and I'm not aware of any hype. The game was made by Arkane Studios, that is all I need to know. I'm not buying it now because I have way to much on my plate, but if it is anything like Arx Fatalis or DMoM&M it is well worth the money.
Ever played Mafia 2?

Not sure, I've played a shitload of games from 2000 to 2005 (or was it 2007), so I may have played Mafia 2 as well. But I'd say my comment about time spent finishing and time spent enjoying still stands, no matter what length is greater.

In Mafia 2 you spend 2/3rds of the time driving around the city. But not in the fun way, noooo drive to fast and the police will pull you over. Never finished that game due to this pointless BS to lengthen the game.

So just like in the first game, then?

Worse. In the first game the distances where much shorter (or it didn't bother me that much). But I also didn't really like the first one because of this. They should release a directors cut of both games with all "non-mission" driving cut out.

I think reliably answering the question of how long it takes to finish a game is pretty hard to answer anyway since every person has a different style of playing a game. Maybe one can estimate the time of a regular shooter on rails. But for a game that gives the player different options to accomplish a goal that's not so easy.

Anyway, I think one can easily rush through Dishonored within 8 hours. But 20+ hours seems to be more "realistic". Or at least, it seems to be possible to spend 20+ hours and more with the game.

http://forums.bethsoft.com/topic/1413477-any-word-on-how-long-dishonored-is/page__st__30__p__21595304#entry21595304

The more I hear about it, the more I like it. What I hear about it, that is. It seems to be rather unclear how long the game actually is, but that seems to lie in the nature of the game. And if it's as fun as it promises to be, then rushing through it is not something I want to do.

Still, stealth in first-person games is something I generally not like. Thief is pretty much the only exception. It seems to have similarities with Thief, but that doesn't have to say anything.

If it's not more than 15 hrs I'm not buying it.

Anybody know if light factors into stealth? Cuz I sure as hell can't tell. All I know is distance + position matters most.

Dunno if this is any help :

http://www.strategyinformer.com/news/20097/dishonored-used-to-feature-thiefs-light-driven-stealth-mechanic

Thanks man. I know about that already, but I'm curious if light still has any place in the game. Makes a huge difference if you're standing in a dark place vs a light place, regardless of distance.