There is a theory which states that if ever anyone discovers exactly what the universe is for it will instantly disappear and be replaced by something even more inexplicable. There is another theory which states that this has already happened.
If you don't mind using the exact same tiled graphics of the original Transport Tycoon, there's always... Open Transport Tycoon. It's actually pretty much the same game, but open to mods to modify vehicle sets, economy functionality, etc etc.