If we're talking strictly games that I like as horror games then Amnesia is the outright winner there. The others I could name are more horror themed than games that work as horrors.

Not trying to be a critic of your favorite games but Outlast just came out yesterday. Can you really call a game "one of your favorite games of all time" if it came out a little over 24 hours ago? I mean, how much game play can you get in on a game in that amount of time?

Sanitarium
John Saul's Blackstone Chronicles: An Adventure in Terror
Gabriel Knight: Sin of the Fathers
System Shock 2
Anchorhead

Da Weclock has come back. *wave*

Call of Cthulhu: Dark Corners of the Earth
Penumbra series
Outlast( im playing it right now really a good game)
Amnesia
Silent hill 2
The Worry of Newport - mod for Crysis

hope to add and play shortly this too

the cat lady
U55
Daylight
Routine
Dying Light
The Evil Within

Yay! Someone else who actually liked Clock Tower :)

Hmm...for me, its a mood thing. The original Silent Hill scared the crap out of me, but I also loved 7th Guest, System Shock, Alone in the Dark, Resident Evil...oh and Eternal Darkness certainly had it's moments too, when your character was going insane :)

There is only 1 game i think of when asked what the scariest game is.... its Aliens vs Predator The Original.

I played this in Quadrophonic Surround sound in the dark as a marine and I scream so loud I woke up my family 2 stories above me as a kid.

I still get sweaty palms when i think of this game.

On a glorious side note AVP Classic 2000 is DRM free from gamers gate for $5

For a modern game, the closest thing I've come to being scared is STALKER that game will rape your mind!

Now that I played I Have No Mouth, and I Must Scream for the first time I also find it very disturbing.

I didn't I found it easy I finished it on Amiga and it was hilarious!

Most of these so called horror games are actually pretty hilarious! they are not "scary" at all.

Oh I understand, well my in that case: Amnesia, Penumbra Series and Cryostasis. I also enjoyed some of the old Alone in the Dark games.

Horror games mustn't always be "scary" like, that there have to be dark rooms and shock effects. There are also storys existing that can scare you in a psychological way and burn their deeper senses into the subconsciousness, if you are able to understand them. The horror comes while you overthink them maybe even unconsciously while you are sleeping, which can result in nightmares. This kind of psychological horror games are in my opinion a way more effective because they reach out of their medium and have a influence on your mind.

Yes I agree all those "scary games" are quite garbage IMHO I like psychological horror Yes!

Favorite horror game of all time has to be Fatal Frame. Fatal Frame scared the pants off of me when I first played it.

I dunno, there's system shock games obviously, then there's Gabriel Knight series, Nocturne was very cool and i hope i'll see it here one day. Ecstatica was horror-ish even though i learned that the best known monster was actually a werewolf much much later, i thought it was a gorilla back in the day :).
Silent Hills are cool, but they went a bit downhill with 4 and later releases. Undying is cool, American McGee's Alice, i even like Phantasmagoria games.
Call of cthulhu is also very cool and Condemned had some quite hardcore moments, Devil inside was also fun.
And ofcourse Vampire the masquerade games, those are one of my all time favourites

and many many more with games like Hell or Harvester, Bloodnet etc.

I just like horror themes in general, so the shorter list would be of horror games i didn't like and that was mainly stupid and boring FEAR, Amnesia and i didn't get very excited about Penumbra and slenderman stuff seemed very silly.