I've been drawn to Hong Kong, the 1920's, the South China Sea and more from the Interbellum years between the World Wars as a possible campaign setting. Time and again real life gets in the way. I've been going over old campaign notes from 2016 from Dragonring Issue #1 Comicbook by Guang Yap From Aircel Comics As D&D Campaign Fodder Possibly using Wretched Interbellum as the go to system to pull this off.
The Interbellum years were wild, the spectre of World War I hadn't quite faded. The Orient was wide open, China was a complete mess, and there were plenty of opportunities for both heroes and assholes. The Wretched verse is prime for this; "The shadows of the Great War still loom large in this uneasy interwar period, coloured by the lingering trauma of unprecedented violence that swept the world from 1914 to 1918. Unsettled borders, crumbling empires, and new regimes leave the political landscape fraught with tension. Strange occult forces stirred by wartime bloodshed now threaten the fabric of reality. You take on the role of adventurers in this uncertain era, navigating landscapes scarred by the horrors of trench warfare. Like the roguish sailor Corto Maltese or Steinbeck's wandering souls, you may have no allegiances beyond your own code of honour. Alliances are prerequisites for survival, yet trust is scarce among scheming factions vying for power in the ashes of war. Moral compasses waver like ships in a storm, the lines between heroes and villains obscured in swirling fog." The lines between heroes and villains were non existent and it was all about profit and getting a piece of the pie. Add to this the Pulp elements and you've got the makings of a great campaign setting that could last for years.
Nazzaruth has been spreading it's cult throughout the South China sea and getting humans to worship it. Nazzaruth has been doing this through 'black miracles' healing the sick, the desperate, and feeding the hungry. There are however prices for all of these 'miracles' such as soul exchanges, human sacrifice, murder, and the usual that goes along with the price that demons extract. Enter the PC's who have noticed the number of islands that have fallen to this cult.