Have you had the chance to see, if Unity lets you build the game for Linux?
Sorry for the long wait, but I'm working on a Linux port. You can download my test version from http://properlydecent.com/data/downloads/BallsyWorldCup2020_v12_linux_x86_64.rar - it would be very helpful if you could give it a try and tell me if it works for you, and what distro you are using!