Whoa, now that is some grade H horror! Holy smokes the tension nearly gave me an ulcer! With an expansion on this you could easily make a very successful horror game! I know this was based on PT, and that game really got horror right. This was an excellent adaptation!
I have so many questions about how you accomplished this! Like what engine you used, how you got that spooky filter, and how you so skillfully warped space around the place! I know the basics, but aside from the doors being the visual barrier, I couldn't see any flaws in the design.
I wanted to do something like this with my own game, but I'm quite impatient and that made it hard to build that tension like you did.
The one scene I felt went on a little too long was the radio scene. I know it wasn't supposed to be 100% clear, but I couldn't make out much with what was being broadcasted, and it ended up taking away from the tension because I kind of got bored after sitting for so long. Otherwise, almost a perfect execution, well done!