Wonderful, mysterious Visual Novel. Had me hooked in the first few minutes and it's unpredictable and keeps up the tension the whole time.
Very lore-rich and fitting music (nothing upbeat, but more subtle and with emphasis on the situation or location.)
Very much recommended :)
And I didn't even finish it nor a route once yet. Just need to stop a bit after reading it without a break for 3-5 hours or so.