Interesting game! I would say the collisions need some work when it comes to jumping up platforms... for the art style you are using everything is so big and close together maybe consider adopting the ability to just jump through the sprite of the platform above, like in Smash Bros. I liked the art style, however I think if you blurred/darkened the background art it would make the foreground much clearer. Sometimes I wasn't sure what was where. Great job on the level design!