I noticed recently on Steam that there are quite a few indie strategy and other indie games (including two space strategy games) available for both PC & Mac.
I remember a few years ago, on the Gal Cil II forum, someone asked whether Gal Civ II would ever be ported to Mac and the answer was 'no' because it was not economical to do so.
Since then there have been big changes in the gaming industry especially with regards to games on mobile devices.
Anyway, fingers crossed that the Gal Civ universe will some day expand beyond PC.