Have you played any of the Mayfair Rails games? They are economic/resource management games in rails trappings. The Mars/Barsoom thing would be mostly a theme overlay. The creative part would be figuring out the commodities and the map. Barsoom is public domain at this point, I am 99.99% certain, so there wouldn't be any copyright issues for that content. OTOH, Lunar Rails is my favorite, and Barsoom would have to be two linked hemispheres just like Lunar. :)