Nice game, but a few things:
1. Maybe use something like squares instead of balls, because they are rolling around really uncontrollably.
2. The color scheme is nice, but the background hurts my eyes.
3. Add music and sounds as well as particles! Some nice feedback doesn´t take long to implement and makes every game better!
4. Add dieing, so you don´t have to restart everytime!
I hope the feedback helped you, would be nice if you could check out my submission too. :)