On GOG, much of the "cross platform" support is using Wine emulation and Boxer for the OS X and Linux game support . DOSbox is used for DOS support under Windows (I use DOSbox SVN-Daum myself under Win10x64.) My opinion is that if you like gaming enough to buy several games a year and play them then you definitely want to be on Windows--as well, you can dual-boot Windows natively on a Mac and Linux x86 PC, and so...it's not much of a problem. I think creating an involved, complex game on Win32/x64 D3d/OpenGL/Vulkan (although the latter API is rather slowly growing) is enough of a job for any major developer--paying other companies to port the Windows version to other platforms later is not without its own set of problems--and extra expense. If you like games it seems foolish to punish yourself on a secondary gaming platform--just imo...;)
