Clever but...
...needs improvement. I'll just cut to the chase and tell you what needs fixing.
The explosions hide the notes (bullets) which makes it nearly impossible to dodge incoming fire unless your just plain lucky. The enemies notes need to be a different color to easily differentiate during a firefight.
I know your trying to base this game around a composers music, but it needs some subtle sound effects for explosion and what not.
The good really out weighs the bad, but there are too many good things to mention. So your going to have to trust me when I say this deserves a 5/5.