Umbrella had successfully created the virus, causing Ghouls/Zombies to run amuck the city, then the state. In an attempt to rid of it, they decide to bomb the city (as in the RE films). Behind the curtains, however, was another organization who had wanted the virus for themselves, one occupied in China. (this is where the fallout story comes in) Threatening a nuclear war, Umbrella is forced to go to war. They manipulate the media as a cover-up for the reason of the US military taking the precautions as to build vaults and evacuate to fight. The cover? The world was running out of resources and the Chinese was going to drain Alaska of the fuel there. The public of course followed along with the story and did what they could to could to fund, only furthering Umbrella and Armacham in their researches and supplies. China then took action when Umbrella refused to hand over the virus. The first nuclear bomb was launched in on the US, where we retaliated, along the USSR, and the world became a deserted, radioactive wasteland. Both facilities by Umbrella and Armacham were built in HIVES (as seen in the RE film), all underground and preserved.
Currently, Alma has been quiet for years until the activity above shook her awake below the surface. Now, she is out for her children along with her forces of Replica soldiers and the hazards of the Wasteland.
WE ARE A FALLOUT 3, F.E.A.R. AND RESIDENT EVIL CROSSED ROLE PLAY GAME