Note: An important note! I've been working on this fic since 2014, and the first draft is complete. Buckle in: this is a long fic, and you're in for quite a ride. Chapters will be added as I edit them, which will at times be a slow process. I recommend following this fic on AO3 if you can; this is only a crosspost.
War. War never changes.
Human history is written in countless battles for resources and power. Shinra did it for the wealth. Wutai did it out of necessity. Even the Ancients, whom humanity has come to revere as the epitome of all that is good in the world, turned brother against sister and mother against son when the calamity fell two long millennia ago.
But war never changes.
In the late 19th century, the discovery of nuclear power changed the weapons company Shinra Manufacturing Works into a world power overnight. Over the next century, the Shinra Electric Power Company would come to dominate every aspect of life on the Planet, from the electric power it brought to every home to the protection it offered through its army.
In this world, mako was nothing more than an addictive substance used to market soda; magic and materia were scarce, considered more myth than truth. The Shinra Electric Power Company built nuclear reactors in one city after another, bringing with them the spread of electricity, modern technology, and culture. Shinra scientists used atomic energy not as a weapon, but as a power source.
Yet as the new millennium drew near, the world's resources began to run out, and peace evaporated. Shinra fought to defend its territory — and its resources — against all who who would take them, particularly Wutai, which had nuclear interests of its own. In time, relations between the two broke down, and the world teetered on the brink of total war. Fearing the worst, Shinra began converting its nuclear reactors into massive vaults — fallout shelters meant to house the population should the worst come to pass.
In the year 2000, a meteor appeared in the sky. Its appearance would be the harbinger of the end of days.
Shinra reported that the meteor would do no more than cause mild climate change should it hit. Few civilians ever heard that broadcast. The last vestiges of peace had evaporated under the meteor's fiery glow. Riots erupted as people clamored for what few resources the planet had left to spare. Those who could fled to the vaults. But whether the meteor ever hit, none could say.
For in the midst of this chaos, one nation fired upon the other — and the Planet burned.