The game breaks at 2200m when you get the golden chest, perhaps she gets the green hair and the sprite is missing ? it's not opensource ?
Viewing post in Celeste (PicoSystem) comments
Thank you, nice work! I was able to complete it now. Currently this is the only good game I found for the picosystem.
(I found one other minor bug if you're interested: if you turn the sound off, resume, and then turn the sound back on, the sound will not work and the game will freeze a few seconds later.)