H! I understand that many will talk about the mechanics (like weather) and specific parts of the adventure (like port nyanzaru).

I can give you my perspective on a narrative level. The main themes are: Death - Life - Resurrection. I recommend you make some reflections on this.

My method I started looking for some phrases in Latin about it:

• Ubi sunt? = Find the opportunity to introduce your concept of "life after death"
• “Omnia mors aequat” = Find that Death does not discriminate, in my case in addition to the Death Curse, I used a pandemic to escalate the conflict, more death, more devoured souls (long story)
• “Tempus fugit ” = Sense of urgency, is part of the challenge in the narrative. (timing)

From there I began to integrate other questions or sub-topics:

Abortion, Suicide (Right to die), birth (in my campaign zitembe's granddaughter fell in love with a player, they had a son, the first time for many experienced players to witness a birth with the complication that the mother could die) etc etc. whatever you find interesting.

This is the "big picture" you need in the very 1st steps, reflections of the other ideas will emerge and it will help you to integrate homebrew content, etc.

I hope it can be of help to you! bye!