Following decades of increased privatization on a global scale and deterioting relationships between international governments, the Resource Wars erupt in April 2052. Over the next two-plus decades, skirmishes major and minor rage as the world's superpowers confront one another. The feud, which has its roots in the rising prices of the world's oil supply, quickly flares into a multi-national rush for control of every available natural resource. Notable events include the collapse of both the United Nations and the European Commonwealth, the destruction of Tel Aviv beneath a nuclear conflagration, China's invasion of Alaska and the United States' annexation of Canada. This period also sees the more widespread use of biological warfare, which proves to have lasting consequences.
With the world crumbling all around, the United States government commissions the construction of a series of subterranean shelters to be built by the Vault-Tec corporation. These "Vaults," as they are dubbed, are designed to house a maximum of 1,000 individuals; only 122 are ever built. As we now know the Vaults were in fact a series of unique social experiments, each subjecting its residents to a different set of factors. The ultimate goal of these experiments was to develop plans for re-colonizing the planet in the aftermath of whichever cataclysmic event required the use of the Vault in the first place.
Games Radar also gets into the Fallout retrospective action with a short piece from PC Gamer's Desslock titled Fallout is a Good Old Game (the reference to CD Projekt's GOG service is deliberate):
Fallout is about making real role-playing choices. It’s about creating a highly customized alter-ego and making distinct decisions that meaningfully affect your character’s journey. It’s choosing either to aid post-apocalyptic NPCs or to punch them in head [Or groin! –Ed] until you hear the lamentations of their children. It’s embracing the seemingly insufferable task of keeping your Mad Max–inspired hapless canine pet alive against chain-gun-wielding super-mutants, and eschewing potentially more beneficial character traits in favor of reducing foes to a “bloody mess.” The game constantly delivers a range of nuanced choices, and considerably fewer subtle alternatives, that collectively ensure players have a highly personalized experience, which is the essence of roleplaying. In terms of offering role-playing depth, Fallout has a paucity of peers, and it’s still worthwhile to track it down if you never journeyed into its apocalyptic wasteland.