Oh, that's nice to know
I read the instructions in one of your other comments and gave the game another shot, since I didn't even notice there were different colored fairies and that you had to press X for the green ones.
Once you know what to do the rhythm part is really enjoyable too :D
I would suggest to give the fairies some more differences other than color, maybe making the green ones fly at a different height or changing their sprite. Also I feel like the poster is a bit too diegetic indicator, and it took me a bit to understand where exactly the right spot was.
After a bit I noticed that you can actually use two fingers to press Z and X at the same time and it won't count as an error.
Despite some problems, mostly due to the absence of a tutorial, I think you did a pretty impressive job considering all the different features in the game.