Join maps

It would be handy if we could start a game that pulls from multiple maps. For instance if you are trying to practice telling apart Peru and Ecuador, you could start a game that uses the Peru and Ecuador maps. I guess you can make custom maps to achieve this, but that is a bit of a pain. Perhaps you could even subtract maps from each other, i.e. play a game that uses all the locations from A Diverse World that are not in An Urban World.

The weird thing about this is that currently high scores seem to be attached to maps and it's not really clear how it would work with these Frankenmaps.