Nice game, but a couple of things could be better:
- The levels get boring, especially the ones where you have to do the same thing 3 or 4 times to get all the keys, I'd prefer less levels but with less repetition. Also the background is always the same, having several different backgrounds would make the game more interesting.
- It would be nice to see how many keys you still need to find and get a signal when you've found the last one.
- I don't like the music, it doesn't fit with the atmosphere of the game IMO.
- Overall, the game is too easy, getting hurt doesn't have any effect and you can just select any level without having to unlock them.
Anyway, good luck with the game!