Disciple of Flame
In my experience, rather than just giving players free reign, give them guidelines to work with. Have a pseudo-narrative in mind but let them decide how things will play out.Good point. My plot brain has been less than creative lately. When I try to think of one that is group-worthy, it usually involves some type of magical/fantasy element. The only times I have successfully created something that is not entirely magic-related is a political marriage between two royals. That would more or less make the prince&princess the main characters though, so it'd only work as a 1x1.
I love sandbox RPs, but like you said, they're difficult to keep going. I've had my fair share as both participant and creator and the people I've roleplayed with don't contribute at all. I've tried pushing them and giving them ideas too but it doesn't work. :<
One of my big RPs I had 6 kingdoms each belonging to an element. Players created their kingdoms, laws, trade, and all that (this was before nation building was a thing mind you) and they were ALL at war. Queue negotiations, treaties, ceasefires, betrayals, sacrifice and the whole fuckin shebang lmao.