Great UI and sound, fun idea all around!
I found a little bug in the code editor, I did some delete abc.exe's, then after executing it and scrolling back up the yellow highlight's y would be off by half a line (instead of being on the text).
I don't know if I'd describe the game as easy, especially if you delete the notes like I did, so I can only give you a half a thumb for sticking to the theme :)