@Tecnho:
I can't stop laughing at your comment. I'm unable to play horror games; the feeling of tension all the time makes me feel bad. The last ones I played were Resident Evil 2 and Silent Hill, I won't say more.
But I think we have to differentiate between games with an ingredient of horror/tension, and those that adulterate the gameplay so much, that they end up being a piece of sh... trying to increase the feeling of anguish and helplessness in front of an enemy, making you bump into the scenery, or complicating your movements with key combinations, while pounding you with Hitchcock-style music.
If you turn up the brightness on a "horror" FPS and don't put on your headphones at full blast, you greatly reduce the immersion, and it doesn't differ much from any run-of-the-mill shooter.
Then I suppose the issue of age can also influence it, as you scare less and less, and if you have a mortgage, you probably won't be scared of anything anymore 
About BIOSHOCK (the first one), I have to say it's a work of art :sisi:, and its narrative compensates for any scare you might get, whether it's from the plot, or from the fights with the tireless Big Daddys. And the one who hasn't played it, should fix that as soon as possible, but don't go around saying it :facepalm:
Cheers! Gamers!