I loved the art style and over all feel of your game. The error sound is a bit to prominent for how often it is going to be played while try-and-erroring through the different puzzles. I also thought it would be great to have some kind of reward (game play wise or audio-visual feedback) for solving the puzzles that don't contain the key, to make the hunt for the random key location a bit more engaging. Mad respect for for how polished your game feels in such a short time, though! Great work!