Infamous is about 15 hours long.

[DaGreatestHope]

The Xbox Man said:
hmm, this is too short!

20 hours should be minimum

But if you leave the pause screen onw hile going to the toilet, then the game could be over 20 hours eventually.

 

 Yea thats how I made Gears of War 1 and 2 last alot longer!