We have started testing the Mac OS X version of UoC II on Steam.
If you currently own the game (on Windows), and you want to try it on a Mac, you can simply install on the Mac, switch to the beta branch and play. This post explains how to switch to beta:
https://steamcommunity.com/app/809230/discussions/2/3003297945133220808/
Please report success, or any issues you run into, in that sub-forum (Testing Branch on Steam).
The game will not be "officially supported" on Mac during this test period. Once we feel it's been sufficiently tested we will enable Mac purchases in the Steam store.
Cheers!