This is a fascinating game concept!!!! I have no idea how to make music in the first place, so playing a game that dynamically generates it based on how I played it was very, very interesting - it was super rewarding to play a part in the process.
I felt like the gameplay was very simple - it didn't seem like which dot in the ring mattered too much, so boxing them in was almost always just a matter of keeping the shape within the same hemisphere. There are a lot of replayability features but I felt satisfied after just one playthrough.