About 11 hours. The game offers to let you start a new file and play again from the beginning, possible on a different difficulty level, with all your items and money intact. So when you beat the game people, SAVE IT ON A DIFFERENT FILE!
My roommate has been borderline sick all week too. I'm hoping NMH was just the thing to relax him and cfure him of his malady, or the thing to make him finally crash hard and get it out of his system that way.