Why can't the windows version of unreal package for osx, and the osx version package for windows?
The reason they're separate is that xcode is need in the process for packaging the OSX version, and VS2013 for Windows Packaging. If you have the source version it may be possible to set up to packaging for the other OS, but you would be on your own to set that up. The functionality to package between OSX and Windows is on the list but when/if has not been specified.
answered Apr 25 '14 at 07:34 PM
UE4 uses OSX SDK / Cocoa API, and those are not available for windows, so that's one reason why it's not possible to build osx version of the game in windows.
answered Apr 25 '14 at 09:27 AM
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