One of the better games to emerge from this era of terrible internet horror fiction for children, imo. Yes, it's still in the realm of jumpscare-heavy creepypasta, but it's broadly well-executed as far as that sort of thing goes, it's very compact, and the difficulty is surprisingly well-tuned. It absolutely will not turn you into a fan of the Slenderman mythos if you aren't already, but if you are the sort of person who would want to play a Slenderman game, Slender: The Arrival is about as good as you're likely to find.