Interesting idea. I liked the simplicity of it to be honest. The dash came in handy quite a bit. However, I noticed a bug where when you die after the ball goes invisible, the invisibility degree (completely or half or almost, etc...) will persist and doesn't reset. So might end up with a permanent invisible ball unless you refresh and start a new.
One thing though, I am guessing you set the angle of bounce to be random correct? I tried as much as possible to control it but it seems it works maybe once and then it just randomly chooses another direction. So was hard to predict where it might land. Felt slightly unfair because of that. Could also be just a bug I encountered not sure.
Overall, you have something with potential. I think with a bit more variety, this could be a lot of fun. It is fun now and challenging indeed. Good work!