Make new toons spawn at random start location in miniscule sub-zone of collosal mega-zone.
Location size zones like a state or province with enough content to level fully without leaving, to have economies with little import out of zone. Fufillment without travel from zone; make travelling very arduous for inter-zone traders, and very extremely plausably deadly dangerous and time-consuming to get to another zone (with limited exceptions). Creates certain cultures based on what can be taken from those zones environment and scavanged spawns from ruins.
Different zones would make differing cultures. Different plants, beasts, antique things from before w/e apocolypse, would make different clothing, buildings, etc. Maybe different ways of saying would crop up in different zones.
Hmm just like the vault experiments.
"you eat That?!"