Thanks for attempting to play despite having a non-optimal machine for the game.
Unfortunately, I couldn't help much. I tested it on two MacBooks that I borrowed, and it seems that the Retina display consumes extra processing power due to the additional pixels it processes on the screen. Sometimes, it even crashed the entire machine (oops). The one with a Silicon chip can run the game with okay graphics. I'm sharing this information for your future reference when testing 3D games on a MacBook. But these issues are not your fault, and you shouldn't feel guilty about lowering my accessibility score.
I understand that it's difficult to introduce a niche genre but at least you tried and I appreciate it.
