Hmmmm, I don't have a way of testing it myself, but I do occasionally get people reporting issues launching the game on mac. Unfortunately, since I know next to nothing about mac, there isn't really anything I can suggest beyond the basic stuff like making sure there isn't some kind of antivirus blocking it. The only google results I get for this error seem to suggest reinstalling python can resolve this issue, but I'd be surprised to learn that python is even required for the game to run (Far as I know renpy games come packaged with everything they need). Is it possible you have some kind of incompatible version of python installed which is somehow conflicting with the game? This is pure speculation, but since I won't be able to reproduce the error myself, that might be about the best I've got.