Well done with producing such a well-rounded game! Sound and graphics are good quality, though I have a personal dislike for the red character (but that's just me!) The platform physics seems a little off, I was able to jump up a block where it seemed I shouldn't have been able to, and in other places it wouldn't let me jump off the edge of a platform, which makes me think this was done in Godot, because my game had the exact same issue.
I got stuck with the door at the top surrounded by rows of spikes, I would like to try different things to proceed but every failure would mean a 5-minute delay as I get both characters to the top again and remember the sequence in which they have to progress so I decided to stop there.
But on the whole this is a great game!