Im not sure if this can be implemented without having to reprogram every map, but it would be great to add another layer to the game if these crossing rules could be put in;
naval crossing-units crossing to another territory by a naval connection roll one less dice when attacking.
mountainous crossing-units crossing to another territory by a mountainous connection (previouslly unpassable in most maps) roll one less dice when attacking and suffer one unit loss before each roll of the dice.