[Haunted]

Must agree that the Silent Hill games created a deliciously dark and uber creepy atmosphere. Fatal Frame also gave a rejuvenating evil to the "haunted house" theme, very creepy.

I loved Aliens for it's sort of "hellish" atmosphere. It completely leaned towards the sci-fi horror, but there was definitely a hellish quality to the place. It wasn't as simple as being taken into an infested space colony. I don't know if I can describe the senses that I get in my head.

My favorite setting which can be made into the perfect atmosphere is the possessed/haunted insane asylum. It sort of plays on itself: the haunted mind, the haunted people, the crimes committed by haunted doctors or other patients creating ghosts, which in turn haunt the people, and create cycles which continuously feed on themselves and lives making them stronger and more vile. Then you've got the idea that the mind of the insane is the most powerful mind of all, because it has no boundries, it can and will believe in or accept anything.