The artstyle is very cute! It gives me nostalgia for some cartoons. Character and monster designs are also really nice. I did have some difficulties with the screen size. I think my monitor isn't high enough and I couldn't resize the game window itself. I don't know if there was UI at the bottom telling me how far I was with defeating enemies or having points ^^' Another thing I noticed was that I could cheat by waiting and just shooting up because enemies would collect at the wall and come down.
All in all, I think this is a very cute game that can have a lot of potential ^^ Good job!!