Borrowed Deus Ex, it gave me one of the best gaming experiences attempting a zero kills all stealth run for my first go round.
Possible Spoilers, but unlikely:
Just before the first boss you take an elevator down into a very sneak un-friendly complex filled with soldiers. I was dilligently working my way to the target when I got peeked, panicked, and began running up and punching people in the face/stun gun/slanging concussion grenades. It was intense. I would recommend it to everyone.