Basic idea was okay, but the complete lack of challenge meant this got old quickly.
I wrote this entire review whilst keeping the game running, and didn't struggle at all to keep the red balls at bay.
Playing this reminded me of -Red- (https://www.newgrounds.com/portal/view/341598) - I'd recommend playing that if you want some idea on how to improve this.
(Final score for this was 364, after I waited for an eternity to lose.)