I think it should have been obvious that I was puzzled rather than angry; I certainly don't want to claw back the 2-3 euros I paid for Arkanoids. But I do feel that if the creators haven't tested their product on a Mac, but are just guessing, then they shouldn't advertise such a version at all; this is perhaps something Itch.co might consider imposing as a general rule, since repeated failures will inevitably reflect badly on the site!