This is really really good!
I don't know how to describe what it reminds me of without spoilers so:
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It's scary not because of what happens, exactly, although that is scary! But also because of the way you learn things -- it's almost the scariest when it doesn't tell you something, so by putting together the pieces, you're realizing something and filling in the gaps. There were a couple of moments that gave me a genuine shiver.
The gameplay and plot reminds me of The Roottrees are Dead crossed with Stephen King's The Outsider (without being derivative or anything!)