Fix thy sound.
Okay, here's the cool thing about horror. The subtler, the better, until suddenly something comes screaming out of nowhere and everyone wets their pants. It's hard to describe something as subtle when it screeches in my ear every thirty seconds. Okay? So take out the screechy bits because a) you're killing the mood you're doing so well otherwise to create and b) you're giving me one hell of a headache.
If you retool your sound design, I will come back and play this game the entire way through, and probably give it a much higher rating.