Nice, i like the art style and the theme a lot. Good work!
I wasn't able to win even once tho, lovest platforms are too high to just jump on them so i had to use enemies (which made me take damage) or wait for the earth boy form. And when on the platforms it's hard to kill any enemies since my bullets collide with platforms, yet enemies' bullets go right through. Best strat is to just climb high enough so enemies don't shoot you but then the arena changes and you'll fall down.
I had several runs where i got 2/4, but i don't remember even getting 3/4.
Some bugs i found: On loss, it shows a black window with two white rectangles. Looks like when walking into the right edge you just fall off the map.