Xehanort was bored.
Ceaselessly he created and destroyed in the void but found no reason to really sit there.
It didn't matter what perfection was established, he didn't see any reason for it to continue on.
His hand created earth. Trees sprouted sporadically, hills waved, but otherwise it was blank as a fresh canvas.
And so the old god sat back, and wondered what would happen if instead of destroying the world he neglected it.
The outcome would be the same, he knew, but his curiosity made him turn his back and continue his endless cycle.
So I've come up with an entire God/Mythology AU. There'll be more just this is a really short establishment of the beginning because literally this is pretty much what happens Xehanort made the world, shrugged, and turned his back on it as an experiment.
Don't worry things get better.