Damn, for something so simple that music really gets into your head! I'm going to be hearing that damn monkey in my sleep.
This was a neat little game. It only took me three or four attempts to pick up the idea (to be fair I'd had advanced warning by watching streams of people butchering their first 20 or so attempts!), but after that I was able to continue pretty much indefinitely. I'm not sure exactly what you could add, but it would increase the replayability if there was some way to scale up the difficulty later into the game.