Official Mac and Linux ports of Total War: Warhammer II are out now, and folks who already got it for Windows have those now for free too. As is the way with Total War, the ports are handled by long-running portpeeps Feral Interactive. While running Windows games on Macs and Linux b0x0rs is easier than it once was, especially with Valve working on Steam's new built-in Linux trickery, it's still nice to have formal support.
Feral used to sell such ports separately but nah, these days publishers have 'em thrown in as bonuses. Getting the game for any OS gets you it for all three.
In other Twar bonus news, Creative Assembly yesterday bumped Medieval II, Empire, and Napoleon up to 'Definitive Editions' which include all their DLC. If you had the base game on Steam, hey, you've now got the DLC too.
See Feral's site for precise details in exactly which Macs and things can run Twarhammer 2. My Macless understanding is: some of them.