I have realMyst Masterpiece edition and Riven (X) neither of which I have finished but do love just wandering about. Is Myst IV revelations separate game i.e. is it worth my buying it and if so are there others

I had the impression that the masterpiece edition of myst included some other versions?

also-it seems on Amazon that they are only available for PC not Mac - is that correct?

these games are the only ones I have found I like as shootemups do absolutely nothing for me and anyway put my BP up (I'm 67)