Very neat, but got kind of confusing when it got to the mixing bits.
Also the whole thing feels like a really long tutorial and that when you're done getting all the new parts that there's not much of an incentive to keep playing. No time limits or penalties, nothing to strive for.
The dynamic way the music can combine however was very cool and this idea has potential for sure. Also the music and art was well done. Controlled well and saw no bugs, very solid