I played Stars! for over five years now, and it really is a great game. I do not know if there is another game like it for the Mac community (I'm a PC user myself), but at this moment the successor to Stars! is in development. In fact, I got the address to the Ambrosia website through a post on the forums of the lead
Stars! Supernova Genesis (the successor) website.
The problem (and maybe your solution?

) is that they haven't found a publisher yet to fund the remainder of the development cost. Maybe this is just wishfull thinking, but with Ambrisia as publisher, there could very well be a Mac, and maybe also a PC version of the game.
Please do keep in mind that I'm just another fan of Stars!, and that I do not know in full detail how the developers at
Mare Crisium think about these things... I'm only here to arouse some interest.

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Confucious say: man who lives in glass house shower in basement.