What is it that scares you the most about Amnesia?

[NGW]

For me it's probably your vulnerability (and honestly I expect this answer to be one of the more common ones), and that to me is what makes Amnesia work so well compared to other horror games. Slap a weapon in your hands and you completely remove that all important element. That's why Black Plague worked so much better as a horror game than Overture did.