- 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
For a long time it traded in leather and meat from Brahmin, but as other places were offering the same goods at cheaper rates, and people began herding and raising their own Brahmin, Modoc has been on the decline. It is mostly a sleepy mountain community, with a centrally located Bed and Breakfast for the traveler. Modoc is beginning to change to a trade city, taking its cue as a stopover place for the Vault City trade routes, but the change may not be enough to save it.
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.