Australia is Earth's forgotten Test Branch server that is just still running ... one day, the other servers got too full, so they had to hastily bring it back into service.

Everyone has a testing environment continent. Some people are fortunate enough to also have a separate production environment continent.

both AUSTRALIA and south america, both continents were isolated for a long time so they both developed unique species. Marsupial has its likely origins in South america actually, since its the other major continent with marsupials, they also have things like sprassadonts(marsupial like), and liptoterns

Best case scenario is that this is his version of The Sims.