I love the overall style of your game so much. In fact, when I first saw the characters, I had been studying what the two straps floating next to the people were. I finally found out that the leg figure was flying in the air. lol The puzzles are also very interesting. If I had to say something about improvements, maybe you could add some door opening sound effects to let users get feedback. Let them know they're using the key. There is also the need to make different doors have different colors, so that the player knows which key corresponds to which door.