Thank you for your comment.
I wanted to be able to play/stop individual notes (e.g. right now when you hit a note it stops playing/won't play). This also means that I have the whole Moonlight Sonata score section in code. I had other ideas but those would have required a much more complex set of note samples and score. Also, I had to stick to music that is in the public domain.
I've always wanted to do a game that has Erik Satie - Gnossienne No. 1 in it, so it was my first pick. However, I think the best match would have been Ludovico Einaudi - Experience. It starts up slow and then really builds up and it has nice note patterns. Though I would have needed 96 hours just to transcribe it.
Good note on the skybox. I was trying to have some balance between mood and being able to see the character (since ambient lighting is controlled by the HDRI skybox). I guess I never managed to get the light quite right. Will keep it in mind for future improvements.