i like it!
could be a the beginning of a story - maybe find a way for the monster(s) to track the player, as it was harder for me to find the monster (wanted to know how it looks like) then the girl ...
the detail of the nightsky with stars is a good one, creating positive emotion, but you should fix the fact that the grid-joints are visible, because if not that is a bit like 'truman-show'.
in your 'how to play'-description is a typo - you wrote 'montser'