Two centuries after the Great War of 2077 that destroyed most of civilisation, Super Mutants, Ghouls, evermore hydrogen-powered robots, and other dangers roam the Wasteland among the descendants of lucky survivors, or Vault-dwelling hermits who still leave their shelters for one reason or another.
Many factions vie for power and control in the Wasteland.
Crack open a Nuka-Cola (and pocket the bottlecap), check your Geiger counter, load the microfusion cells in your laser pistol and hope there's no Deathclaw around the corner. Because war...
War never changes.