Could've been better
This was a great idea, not so well executed. My biggest complaint is with interactivity. Timing the beats/melodies/vgsounds/other so you can make it all sound good can be hard - and annoying.
I also agree with chemboy69 that it would've be better if you made a button to stop each sound. That would certainly make it easier to mix the sounds, wouldn't require you to memorize which button plays which loop, and the whole experience would flow more naturally, and the player would have much more fun.
I'm not saying you were lazy or that improving all this would be the easiest thing, I'm saying that perhaps your game would be 1st place of the week, join the 50 best of all time and I would certainly give it a 10. Still, I find it really stylish. Sorry but I have to be honest with my score.