Amnesia: The Dark Descent, a first person survival horror. A game about immersion, discovery and living through a nightmare. An experience that will chill you to the core.
I played this not long after it was released but never remembered to rate.
This game is without a doubt one of the best games I have ever played, it's now 2013 and it's at the top of my recommendations list. It's a far bigger game than being scared all the time; it's so profound in terms of story telling and understanding the position of your character. It's deeply disturbing (in a good way), as you're making your way down dark corridors, wondering what is beyond the door you're about to open, whimpering as you turn a corner.
If you have not played this yet (unlikely), and you're thinking about playing it, do yourself a favor; play it, read every note you pick up, look at every picture you find, and most of all: have fun!