A fun little experience.
You got me to play again with your 9 coins tease (I did not expect the boss to be destructable).

It was odd to me, that the melon who was begging me to save it was used as a thrown weapon which gets smushed when hitting enemies or walls, as well as there being an unlimited supply of melons to throw.
I think it would have been a better idea to throw the melon in it's large form and it ricochets from the walls and then comes to a stop and you have to pick it back up again.

You could improve the level design with some very basic shape language guiding the player. I ran a lot in dead ends because there were no real indicators and a lot of the rooms were so large they did not fit on the screen.

Cool game! Simple but very satisfying. I especially like the enemy design - super trippy. Two things id suggest is adding some kind of health bar or system of showing the health, and also perhaps to make it fit the theme better, make the projectile guy only be able to be thrown once (more powerful attack that way maybe?) and the main character has to pick him up.

Liked the music, and it really shows you put a lot of effort into this game.

Some things to consider:

The walls are a bit noisy, they take the focus from the game because there is a lot going on in the walls. Because of that, most of the games use a blank color or very little details in them! 

Same thing could be said about the floor. It's more than enough to put a few fixels in order to show texture! 

I would also zoom out the camera a little because when the monsters enter the screen you don't have a lot of time to react. 

Well done!