XVII should be japanese folk based.
I've had this idea for the longest time. Core party should be a Samurai male co-protagonist, Ninja female co-protagonist, a priestess acting as a white mage and a naginata wielder dragoon.
They embark on a journey to save their home town from bandits who say they are under shogunate orders. After securing their people inside a mountain cave that could serve as main hub for the majority of the game, they travel to become stronger, seek the auspices' blessing, obtain relics (better weapons), and help other towns who have been raided as well.
Imagine, a childhood love story, sacrifice, kabubi theater, yokais and interdimentional monsters, who are the true big evil.
You don't kill god in this, you don't battle aliens, and the most modern technology you'll see is foreign steampunk shit.