looks great so far..
I got to chapter 2 and noticed a mistake... (not sure if it's on purpose)
when you reverse the gravity and your guys are upside down you invert the stick control.. that's not intuitive.. I'd recommend keeping the stick doing the same movement even though you are on the ceiling... I think it just makes sense to do that when controlling 1 player, nevermind your game where you control 2. What ends up happening is that since you invert the controls, you end up thinking you are controlling the other player.
If you were going to do such a dramatic thing (invert the stick) I'd make it VERY clear, and introduce that mechanic slow. And that would be a very advance challenge...
the music is a little repetitive.. I liked it better with no music.. but that's me.. I'm a super snob when it comes to game music. I hate mindless loops. btw the music currently does NOT loop seamlessly which makes it that much worse.. there's a small space between then end and beginning...just needs to be cut currently.