I will admit I found this annoying and fun at points, however my biggest problem with this is originality. The original Slender game scared me to death (and still does!). And yet, your 2D take on the game does little to scare me and really doesn't improve much on the design of the original. A 2D version of Slender would be interesting, were it to have different graphics, maybe a different perspective, a new map (and not just a 2D version of the original slender's map).
I applaud your idea of a 2D version, and I also applaud the music, as it hearkens back to the creepy aspects of the original slender. However, this game lacks originality and further development from the original. Maybe a new map, a new game mechanic, or some other item should be added to differentiate it and make it a new development along the way in the line of games influenced by the Slenderman mythos. As of yet, this game is most definitely an enjoyable experience. But I just can't see how it adds anything to the series.