In a lot of discussions on campaign settings or various facets of.D&D "lore" (cough, Halflings, cough), I see folks focusing a lot on the logical or illogical rules of a fantasy world. How could Halflings societies thrive if they don't interact with other cultures? How could the smithy be a dwarf without there existing large dwarven cities? How could the main city survive without extensive farmlands, and how are those farms not constantly raided by monsters?
I'm always surprised by these issues. I've come to realize it conflicts with a central theme of how I create my homebrew campaign rules:
No aspect of the setting exists if the characters are not interacting with it.
In my campaign settings, I create some very loose ideas about the themes and aspects of the world ("there are vampire tyrants" or "it's all one huge kingdom"). But any specifics are kept undefined unless the characters need them (or unless the players show interest). Though the campaign world looks fleshed out and immersive, behind the characters' backs it's all foggy and insubstantial.
Here's an example of what I mean:
In a recent campaign, one of the characters was a cleric of Arawan, god of death. I made sure Arawan had a presence in the campaign world, but I did not have any other firm truths about religion. (No player showed much interest in religion during character creation, so it didn't get detailed.) During one adventure, the characters came upon a huge turtle in a swamp. I'd decided this was the spirit form of an animal god once worshiped in the valley. The characters were really interested, so after that session I created a pantheon of animal gods. Some were still worshiped, some were forgotten, others were corrupted.
As the campaign went on, one of the players became really invested in these animal gods. He started theorizing that they weren't gods, just powerful beings who had tricked the people of the valley into worshiping them.
Well of course that became the truth!
These animal gods became a very important part of the campaign.
Meanwhile, other seeds I'd planted for interesting ideas were either ignored by the players, or not interacted with by the characters. I either shelved those ideas, or changed them so they'd come up later. For example, I had a slime-focused dungeon that I modified and leveled up three different times because the characters didn't choose to go into it in the first two locations. It went from a polluted coastal island to an abandoned swamp temple to an ancient alchemy lab. Once the characters explored the alchemy lab, those other potential dungeons ceased to exist.
To reinforce: this is just the way I prefer to run my homebrew settings. I still have fun thinking about the rules and truths of the world between sessions, but unless those rules and truths are needed by the characters, they are not set in stone.
So what do you think? How do you run it? Is your campaign setting realized and existing even without character interaction? Or do you only detail what the characters are interested in?