Very cute lil game! I think it definetly needs more work design-wise but there is potential here! Most of the time spent in game is just trying to catch up to the ball, even after I got the bowling ball upgrade it was still super hard. There were a lot of situations I felt I SHOULD'VE hit the ball but didn't somehow, like when it is immediatly above me and so on and the last thing is the impact of the ball. I'd highly suggest looking into making the ball piercing or something along these lines because it feels very unsatisfying to chase a ball for half the wave just to finally hit it and kill a single enemy LOL
Other then that you have an amazing base for a game here and I can't wait to see where you take it!