How about this. Please be gentle, I am writing on sudden inspiration.
The 3rd installment assumes you ascended to god hood and in the beginning you get some kind of dialog option to choose what kind of God you were which will effect some later game content.
You wake up in a forest, dirty, torn garbs on your body and.... wounds? You feel the realization like an electrical shock in your body. Blood pumping, heart beating and flashing pains om where you've been hurt. You can't remember the last time you felt any of this. It was so long ago you were mortal that the experience you have now is overwhelming.
You take some time to adjust and then stand up. Strangely you regognize your surroundings. Even though it is overgrown with moss, shrubberries (bring me a shrubbery!) and trees you can se a familiar foundation of what once was a large compound (candlekeep my friends, yes indeed).
The storyline would go something like this. You have been god for a loooong time and in the human world a lot has changed. For some reason (clumsy/greedy God, human rebellion etc.) the gods have been forced to walk the earth again, just as what happened to your biological father. It's now up to you and all your accumulated experience and knowledge in the matter to make sense of the situation and decide what you want the outcome for the world to be. A long the way you might take some companions to learn more about this new world and maybe also some people who have met the same fate as your can tag along.... Gods, now mortals. The world is in chaos, and if you thought wild surges were bad, it is nothing compared to the ride your in for.
It follows the same storyline, has the same PC but could be entirely different. Hundreds or even thousands of years have passed and the world look nothing like it used to. Those gnomish inventions you saw in
SoA was just a hint of what was to come. Maybe even evolution has tweaked something? Everything is different. No Npcs from the past! None.
You will also not be some insignificant wanderer like in the previous installments. You are an ex God whose choices have changed the world. You are not just a person, your an historical current personified. Possibly you have some cult following or properly organized church to your honor.
Now please don't trhow reality first thing, straight in my face. Maybe you could play along a bit first if you like it?