Such disappointing backward progress. They obviously have developers who know how to write cross platform, since they are also targeting consoles. Would it kill them to compile and release unsupported Mac and Linux binaries?
This is likely very much on Apple for depreciating OpenGL for a proprietary standard, making cross platform development a hell of a lot of work for such a niche market.
Combine that with the lack of Nvidea drivers and Macs are in an especially dismal place for 3D gaming for the forseeable future.
I've read that it'll be available for "PC, PS4, and Xbox One."