Hmmm, haven't tried amnesia yet, might check it out once I get a better GPU.
Regarding the other games... Well, you'd be pooing bricks while playing Dead Space. That, however, would last only about a third of the game, tops. You'd simply get used to everything too fast. F.E.A.R. is decent, but again, you can easily see the pattern: an area of human soldiers, an area of mindfu--, another area of soldiers, another area of... you get the idea. Haven't played the sequels to either game, so I'll refrain from commenting.
There's another series of games that few have mentioned so far. They're not really horror games, but the creepy atmosphere is always present. That's right, the S.T.A.L.K.E.R. games
Of course, there are some areas that will make you cry "mommy!" too, but you'll have to get past the first few bandit and military infested areas to get there.These games are not really what you're looking for at the moment, but they're pretty damn close. The horror feel can also be enhanced with user-made mods, so you might want to check these games out later.Edited by Hyoketsu - 5/7/11 at 4:48pm