I run Linux and I know some have OSX. It would be good for judging if you do the relevant OS builds.
Really? interesting I wonder why if the have the tools, the would make it that hard.
Unity can build all 3 with just a few clicks.
It looks like unity has a prebuilt core player module and is only compiling the support scripts so it can get around the limitations for targeting created by Microsoft and Apple.
If anyone has questions on how to export for other platforms via Unity, let me know I can answer.