I'm an Survival Horror fanatic. I've played through a lot of horror-games and I feel that I have to ask the obvius question. Which is the scariest game you've played.
For me, it's Silent Hill. The first time I saw the game it was at a friends place. He didn't have a 60 Hz TV back then and he had the NTSC US version of the game, so we had to play it in black and white (you should try it sometime XD). That made me look into the genre and of all the games I've played or seen, nothing beats the scare you get from Silent Hill. The school and the hospital are two of the most scary plases in gaming history.