Congratulations on releasing this sweet little game. It took me a while until I figured that the Morse codes are also available inside the game. Having the codes always be available would be appreciated. I can easily write them down myself, so why not present them in the main view? I like how the different materials produce different sounds, nice attention to details. The concept can be further developed by introducing more codes as the game progresses, you already have a nice core gameplay loop here.
Good luck!