This is fascinating and super cool. Well done!
I have a couple questions:
-How easy would it be to use this to, say, build a Quick Time Event where timing/frequency of the button press would be based on the music currently playing? Like, how malleable is this for non-programmers =/
-Currently, I think you can mash on all arrow keys at the same time and then get a perfect score. Would it be possible to add a "miss" window, so that if you press the key too early it registers as a miss?
Once again, congratulations on making this amazing thing!