I'm seeing a lot of possible entries missing from the poll, but let's be honest... you'd need a page all by itself to list all the potential choices.
bovius said:
Feeling the need to throw another option out there - the Shalebridge Cradle from Thief: Deadly Shadows. Easily scarier than anything else I've played, including a few of the games in the list above.
Can I get an AMEN, brother! You can search YouTube for a video I put together of the Cradle. Easily one of my favorite, most creepy gaming experiences in recent history. Jordan "Null" Thomas was primarily responsible for it, and a while back he dropped by the Through The Looking Glass forums to talk about the making of the level with us. He's an all-around cool guy and an amazingly creative producer, and I'd buy any game he headed up. Along with an extra pack of underwear.
Seriously. If you've played through the Cradle, I only need to say two words. The Door. I spent five minutes at the bottom of those stairs with my bow out, just waiting for whatever was coming down at me.
I'll also agree with Ravenholm (the screams in the distance always made me stop for just a second), System Shock 2 (some of the best sound and voice work EVER), Eternal Darkness (never did get to finish it) and Deep Corners of the Earth (had lots of problems, but some areas really shone through). Penumbra was pretty good too, though half the horror factor came from the fact that you were nearly weaponless and not all that fleet of foot.
I'm rather surprised FEAR never got a mention. True, the scares were a bit cliched for any fan of Japanese horror movies, but even as jaded as I am, Alma seriously creeped me out a few times. There's this one moment where you're watching a live camera feed on a monitor in a security office, and slowly her head rises into the shot; just as you're about to see her eyes, the image cuts to static. I don't know why but that really just got to me, somehow.
I'll throw in a possible surprise entry here: Delta Labs 1 from Doom 3. The bulkhead opens to a dark corridor lit by only dim emergency lights and the ruddy red light of a Martian afternoon. It's quiet... too quiet. After fighting through so many demons out for your blood, the fact that you're only faced with darkness and disturbing sounds for a long stretch can put a player on edge- every dark corridor might hold something new and terrible, and was that noise something growling? Honestly, if the game had tried a bit harder in that vein, messing with the player's head ("They took my baby") instead of confronting us with Monster Closet #482, I might have enjoyed playing it a lot more.