A) Kill dudes but only the ones who will get you points
Use weapons that are in vogue to get extra points
C) Fulfill your needs! Eat, Sleep, and Poop but don't get murdered while doing these actions
The fun comes from the uncertainty. You don't know who's stalking you and your victim won't know you're the one looking for them until you actually attack. As you play your needs bar will decrease and you'll need to refill them at props that are lying around the set. When you do though, you're incredibly vulnerable.
I've got it on Steam but its also an XBLA title. Who wants to play?!