- Major characters
- The Chosen One · Tandi · Joanne Lynette · Dick Richardson · Frank Horrigan · Ken Lee · AHS-9 · Harold
- Dogmeat · John Cassidy · K-9 · Marcus · Myron · Skynet · Sulik
- Major factions
- Enclave · New California Republic
- Minor factions
- Brotherhood of Steel · Hubologists · New Khans · Shi
The Slag population steadily increased since the Sealing. It soon became apparent that they could no longer survive underground without further supplies. So the Seal was broken, and they once again looked to the surface for survival, creating a small farm some years prior to 2241, which to the people of Modoc looked as if the farm appeared out of nowhere.
The game takes place in the year 2241 on the West Coast of what used to be the United States of America, mostly in California and Nevada. Faced with the worst drought on record, the village elders of Arroyo ask the direct descendant of the Vault Dweller, referred to as the Chosen One, to retrieve a Garden of Eden Creation Kit (GECK) for Arroyo.