Hey Killer300,
Unfortunately, I only have a 10.14.6 Mac to test on these days. It seems to work on there, so it's probably something that broke in Catalina. We've sort of moved our development away from Mac especially after the gatekeeper changes.
There are a few things you can try though. If you can turn off full screen, that might help with the issue. We also have a button on the options screen to toggle the Custom Cursor too. It's pretty weird that you don't get the custom cursor drawing, but that toggle is there to help with comparability issues.
The trick is probably getting to the options screen without a cursor. I don't have a lot of advice for that. You will get mouseover hover colors even if the cursor is somehow invisible. You can turn Expose on and off on your mac to briefly see your cursor. You can also maybe open the force quit menu to see the cursor while the game is running. Not sure if it will minimize the game or not.
Hope that helps!
-Andy