This game was really well made but I got stuck at the piano for so long because I couldn't play notes while holding Z and an arrow key until I switched to WASD and Z. this made me discover a thing called keyboard ghosting which is a physical limitation of some keyboards that stops them from registering certain combinations of 3 or more keys being pressed at the same time. so it wasn't your fault at all that the piano didn't work for me but you might want to rework the piano controls so you don't need to press 3 keys at the same time so it doesn't happen to anyone else.