Apple's Game Porting Toolkit is now being evaluated by developers and journalists. It turns out that even without any code changes some of the games could run pretty well on the Mac.
Some additional tweaking by game developers could help improving performance and minimize overhead caused by this translation layer. Essentially, Game Porting Toolkit is Wine patch that allows DirectX 12 commands translation into Metal.
Apple Developer: Apple technologies for game developers
- Bring your game to Mac, Part 1: Make a game plan
- Bring your game to Mac, Part 2: Compile your shaders
- Bring your game to Mac, Part 3: Render with Metal