@ha1da right so what we came up with is that we start from a normal historical time period, 311 AD in the Roman Empire in this case, and have a divine apocalypse occur and change the world as we know it into something more fantastical but deadly.
In Elden Ring terms basically in 311 the Elden Ring or whatever keeps the world working in proper order breaks and the Shattering follows with demigods, deities and heroes dying and transforming the world into a blend of real-life history and fantay.