I haven't played Silent Hill, but the game that has affected me the most fear-wise is Eternal Darkness: Sanity's Requiem. Instead of going purely for a "Rar I'm a demon be afraid!" track, it manages to claw into your mind, and make you love it while it breaks you down. The insanity effects were always great and surprising, and several things managed to make me jump. I actually turned my game off during the "Memory Card Erase" thing, only to realize my stupidity after it was off, which left me giggling nervously afterward. ^_^;;