Fallout: The Beginning

After the atomic war, nothing was ever the same as before. Creatures underwent horrific mutations due to the radiation they took in, most towns were destroyed, and the world was changed forever. For the people, it depended on how lucky you were. The lucky ones managed to get into vaults which protected them from the nuclear blast, albeit some vaults were used for Vault-Tec's own scientific experiments. Some were caught in the blasts and perished, leaving burn marks that would stain the ground or crumbling walls for generation. Last were the ones who got caught in the blast, but didn't quite come out the same. The Ghouls. They got extended lifetimes, but suffered severe physical damage, altering their appearance hugely, to the point where some people couldn't bear to look at them. But the worst part was that some of them never stayed sane. The radiation slowly rotted their brains from the inside, till they went feral, scouring the world, and ravaging anything they saw.

This story's protagonist is John, a lucky person who was a descendant of the war survivors. Born into the vault, it was all he ever knew. He had no idea what laid outside the huge, cog-like door, and never bothered to. Why would he need that information? It wasn't as if he'd ever be out there. But one can never factor in random chance happening.