Bioshock. The part where you're in the room about to kill a surgeon and suddenly there's thick fog and he's gone. I expected what was going to happen next but fuck I was so shocked when the fog reappeared and he was directly in front of me. I think I wasted an entire magazine on that one.
Also, the same thing in the morgue with the shadow that's suddenly gone when you're round the corner but on your way back you get jumped from the dead people storage thing (what's the name again? Damnit).
Also, the same thing in the morgue with the shadow that's suddenly gone when you're round the corner but on your way back you get jumped from the dead people storage thing (what's the name again? Damnit).