I love the visuals and the in game models. The music is fun also and I love the color pallet. Here are some feedback for future improvement:

• Controls on PC: I tried playing with an XBOX controller as well as keyboard and mouse. I could not find the button for attack on the controller and I could not find the button for jump on keyboard. Maybe see if this can be improved and maybe have a screen showing the controls before the game starts.
• Attacking: The attacking action/animation could be improved. Maybe give the character a weapon and make the spike balls thrown a little more spaced out. Currently when I hold down spacebar the character spams the balls so much that it kinda looks weird.
• Level Design: I was having a hard time figuring out where all the coins are and had to go back and forth across the level a few times, maybe subtly indicate areas of interest where the coins might be using level design tricks

Overall nice prototype, could be fun with improvemetns.