Reminded me of Alan Wake. And probably some Stephen King's story (at the least he had similar concept in one of the books in "The Dark Tower" series). Not that the concept of a story blurring the distinction between a story (book or movie) and reality is unique, but it's more the atmosphere.
A lot of things here feel absolutely random, but that randomness serves a purpose: you need to start questioning everything, and trying to find logical explanation. Will you succeed in that? Maybe. Will you go insane wile doing that - most probably.
It is also peculiar how certain minimalism in technics (let alone CGI) is able to provide a much more immersive experience compared to modern movies, too. It's all in the camera-work, the lighting, the sound design. Everything is for the sake of the atmosphere, that will make you unnerved quite a lot, although probably not "scared". The only downside is that in the end, there is no release. I think it makes sense in a way, considering the overall story, but still left me a bit wanting.
