It'd be pretty cool if you added more unique upgrades, ex: the basic ball being given optional effects to set it aside from other balls. Also, I'd be willing to pay money for this :eyes:
There will be an experience system for the balls, and you will be able to swap balls for many different ones with unique properties (that's why poison ball isn't there, I felt it shouldn't be one of the original balls). It will probably be a long time until I finish development (goal maybe this summer?) and I recently created a devlog page for it, you can check it out at https://secretcoder123.itch.io/idle-bounce. I plan on making it free if only because I want it to be available to kids the way this one was to me (: Thanks for taking interest in my project!!