I've really enjoyed this game but have absolutely hit the end, for me.
At prestige 7, my first planets are too small to see, and trying to guess where they are worked for the first but the combination of lag and invisibility meant I'm unable to find the second planet.
A fix for this might be to have a minimum planet size (no matter which planet, it can't be less than, say, 20 pixels across), or to start on a later planet depending on how far the player got on their previous run.
My second observation is that lag becomes a bit of an issue on higher planets. Is there a way of planets have a maximum pixel size to reduce this? Increasing hardness might be a workaround for balance.
I hope you continue with this project, it's a lot of fun to play!