What scares you?

[Rowedekhelicon]

Some of the scariest, pure adrenaline moments for me have been when I knew where the enemy was, but I was hiding and hoping to god I wasn't found - that or being discovered and having to run for my life! 8-O

Thief is one of the best games ever created. B)

That wheezing sound the zombies make is one of the most unnerving sounds I've ever heard in my life! :-0 So adrenaline moments aside, I'd have to say the use of sound more than anything else is the key to creating fear. Penumbra has a great ambient vibe for this effect.