I really like the cup-head inspiration (I assume). Good work on putting this together in 3 days.
I would agree with the other comment that it's actually very difficult. I think the control scheme isn't very intuitive, and having to manage moving, jumping and shooting with one hand is not easy at all, and on top of that you must dodge the enemy attacks :o
I think if there were fewer gaps between clouds, the player could focus more on attacking and dodging with intention - that would probably feel a bit better.
Still, good effort overall