Oh man. I was getting frustrated because pressing Z did not work for me. Then I realised it might be because I have a QWERTZ keyboard. You should maybe add a disclaimer. It's strange because I would assume the engine handles that automatically. Which engine did you use?
Anyways. I really like the atmosphere you have created with the assets. I was only able to unlock the wings with my flute though. I've tried to play the notes in other places with hints like the telescope but it didn't work so I got stuck... happy to try again though with a few more explanations!