Lots of video game tools/middleware work only on Windows, and only recently other platforms have been considered like OSX, Linux, and others. AFAIK for OSX the

Lots of video game tools/middleware work only on Windows, and only recently other platforms have been considered like OSX, Linux, and others. AFAIK for OSX the only legal option is colocation - e.g. you provide an actual OSX machine, and it's installed for you somewhere for your use or your team (I'm actually not completely sure there). I'm talking about OSX, since lots of these tools above are released for Windows and OSX, but not for Linux (yet).