SPOILERS AHEAD
This is really good, very polished. Audio is really nice. I like how you told me nothing about the controls, took me 2 rounds to figure out u can catch the balls and throw them. I've also tried making skulls shoot each other. The exploration of mechanics was a really fun experience :)
One bug I found: when i threw the ball and it bounced from another ball back to me, it showed that I've caught it but I didnt actually have a ball (I couldn't throw it and had to pick up another one).