This is actually a new genre.
On Netflix this film was labeled with "horror" and "suspense".
I would call it: "an exciting , dramatic psychological mystery".
Perhaps the only reasons why this movie is so underrated is probably because there's an anticlimax towards the end, that could be understood, but which probably won't be acceptable to the masses.
Moreover, in my opinion, this film has an open ending. That can be difficult for many people because there are no solutions to all of the complex problems that came along in the film's story. That can irritate/sting.
However, it can also be food for thought or to exchange ideas with others.
As such I'm glad that the creators of this film probably stayed true to themselves instead of submitting themselves to what the masses could accept/like.
What I found really strong in this story concerns what possibly might be the theme of this film: "Nothing is what it seems and reality turns out to be way more out of control and out of the ordinary than you can think or you're used to, and usually things don't go the way you want or hope.
The acting was good / excellent and the way the scenery was filmed showed the breathtaking beauty of Austria.
Thanks for this film.