Best suggestion, add 1 or 2 extra targets to the default view, increase speed of slowest balls by 25%, decrease the fast ones, and increase their sizes, both by 25%.
Increase base gold earned by ~33%
Don't listen to haters. You have the bones of a great game, just don't get bogged down in too many extraneous features and keep the core gameplay intact - with updates, of course
My $0.02
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