There doesn't seem to be mention on a Linux version at all, rather just a Mac version.

I have to wonder, if you create a Mac version of a game how difficult would it be to port it to Linux?

I understand that games designed specifically around Windows (and therefor DirectX) are going to be a pain to port over to a platform without DirectX.

Surely though Mac versions of games are all based on OpenGL and most Linux distributions have OpenGL support too (as well as both being Unix type OSes) so surely the port is not that difficult?

It almost seems justified to have some project that aims to make it easy to port Mac games to Linux, if that was the case then you would see a massive increase in the number of Linux games available.