A great idea. I like the concept of playing notes to make different colored platforms appear. It’s definitely a tricky game as you have to time the notes correctly and press/hold them in the right order. I wasn’t able to get past the sky part. I had trouble getting the rhythm right and remembering what notes I needed to press. It seems you need to master memorization and rhythm, which offers a nice challenge.
I also liked the music and the pixel art. The music fit well with the magic/fantasy theme of the game.
I think the game could benefit from something like more checkpoints in individual areas to make things a tad bit more lenient when you fall.
Overall, I think it's a great concept. It’s almost like a combination of a platformer and a rhythm game. Nice job!