This is great Troisnyx!
The instrument choice is excellent it almost feels child like, making the feeling very creepy and unsettling. The piano playing is excellent, it's very tell-tale and carries an underscore very well. Many people will comment on repetition but I think it really works here. It establishes a mood, very much like older horror flicks like Halloween, Exorcist and Nightmare on Elm Street.
Your hummed singing is brilliant, it's extremely DonnieDarko, enhancing a dreamy state and uncertainty throughout. The combo of ambience and glock is where I feel it shines instrumentally because it embraces the concept of a childlike setting, almost like a wind up toy, but with dark energy and quality. All the instruments sit very well and in their own space.
The melody is great, and very listenable. It's memorable and actually quite catchy. I think at the ending things end quite upbeat, personally I think keeping it dark may have been quite nice. But this is personal preference more than a problem with the song.
I really like your track, it has a lot of '80's' qualities to it, they never make horror themes like this anymore, and I really miss them.