
Originally Posted by
Raype
It uses an exp system.
You only get exp by carrying out actions.
20 hours is a rough estimation of player skills and modes used, objects hacked, vials located, sisters saved, victories, total kill count, times being/killing the big daddy, and methods of killing.
If you're idling, it'll probably take a couple hundred. And at least one person will have to keep playing the whole time.