A ‘relay book’ with numerous well-known contributors
Not sure if this idea exists already but… a famous author writes the first chapter and passes it on for his chosen author to write the next chapter, and so on.
It could even be non-fiction where a scientist or historian gets the ball rolling.
Another twist, ic could be online and paid subscribers could read each chapter as it goes live.
Think of the creatives that could add to the tale and where the journey could take you…