Simple: What is Fallout Earth?

From Fallout PnP

Fallout Earth is the setting in which Fallout games take place. In the Fallout Earth setting, twenty-first century America descended into an era of paranoia and mania similar to the 1950s. The U.S. government became more and more militant and aggressive against real and imagined enemies. Other world powers were often just as bad. As the world’s fossil fuel supplies started to dry up and conversions to nuclear power lagged, people became desperate. Somehow, at the height of hysteria, someone launched nuclear weapons. Those who did not die in the following exchanges lived in darkness or misery for decades. Living in subterranean vaults or frozen in cryogenic chambers, humanity persevered. The Core Region was one of the first areas of the world in which significant interaction emerged, eighty years after the war. Though many regions of the formerly-civilized world are waking up, humanity has a long way to go if it is to ever stabilize.

J.E. Sawyer's Simple system
Introduction	What is Fallout? | What is Fallout Earth? | What is the Core Region?
Simple	Simple Overview | Character Creation | Primary Attributes | Secondary Attributes | Derived Attributes Traits | Skills | Perks | Karma and Reputations | Vital Status | Actions | Advancement
Equipment	Survival Gear | Weapons | Ammunition and Fuel | Armor | Chems | Implants | Books | Tools | Vehicles | Workshops
The Fallout World	North America | South America | Europe | Asia | Africa | Australia | Antarctica
The Core Region	Geography | Sites | Organizations | Personalities | Critters