This was a good level of platformer with shooting for a horrible player like me. The shooting was very good, as in the animation and sound effect. I also liked that the sword slashing was purely movement of the mouse, since that's an interesting layer of difference from the other weapon choice.
The slime graphic is cute. Backgrounds and other arts are fine since the gameplay is the forefront of this, I assume.
There were moments I got stuck just a bit. I was expecting the tutorial to tell me how to open the door instead of reading it from the game description. Also, when I got to the skulls section, I shot at them to test if they were enemies. When they didn't die, I assumed they were just decorative, so I touched it and died. Could just be a me thing, though.