Very interesting and clever concept. The game was surprisingly fun for how simple the mechanics were.
It did suffer a bit from its presentation in my opinion. It felt a bit eye straining and hard to follow at times (especially during the last level). Maybe because of everything switching positions at the same time and the diverse moving background (which made it a bit harder to focus on the foreground). Most of the time I only focused on my character and one or two enemies closest to me.
I think there could have been some more indications, for example enemy sights or how many balls the player currently carries if you consider to expand the game further.