Visit over 30 different cities across the United States. Meet over 150 different characters in all the cities. Plan your journey strategically making sure you're stocked up on food to keep yourself alive and fuel to keep the train moving.
After you enter every city you can go out and scavenge for materials in the cities, break windows, lock pick doors, chop down some wood from the trees and do whatever it takes to survive this disaster. If you're feeling adventurous enter some the radioactive parts of the city to find better loot.