Slender

Watch the vid first and then if you still fancy having ago... the good news is that it's free! Obviously it's a niche game, not for everyone. Not as scary as another indie title I own "Amnesia Dark Descent" but it had my heart going on the first playthrough. I only made it to 4 pages before getting caught.

http://uk.ign.com/articles/2012/07/07/slender-is-pure-horror

I don't know for sure but I should imagine that pretty much anything should able to run it.