I'm trying to break my habit of prep, prep, prep, and never play. I'm looking for a more holistic approach. Imagine having a game world that can be everything you want it to be, where you aren't pigeon-holed by pre-generated content. Imagine a world that holds as many surprises for you as for your players!
I'm talking about a fluid setting: Basically a name, a high concept, and a sample starting location. Everything else is generated by the GMs imagination only when they need it.
It's still just a rough idea, but this is what I got so far...
Zen Campaign World Design
Thou shalt not make a world map!
Once you make a world map, the world becomes finite. There's nothing left to explore if it's all been decided ahead of time. As long as there is no map, the world is infinite. Anything, or anywhere can be in it.
Thou shalt teach the players of thy setting through their adventures!
The only meaningful way your players will get to know your setting is by experiencing it through an adventure. Therefore, don't start making maps, make adventures and let the adventure dictate what it needs. Just keep track of what you create in case your players want to return to that location. Through the adventures, the world will begin to coalesce.
Thou shalt think like an 80's toy executive!
You have an idea for a cool location, villain, creature, or item? You need to put it in an episode before the kids will buy it. Use an adventure to showcase the new content.
Thou shalt give the players the freedom to add to the world!
By not spelling out every detail in the world, you give the player the opportunity to add things they would like to see in your world. Players that have the freedom to create their own character concepts will be more invested in them than a player whose has just randomly rolled some background items that will never come up in game. If a player decides that they want to be a Witch Hunter, that feeds the gm information about what that player would like to see in the adventure.
You see, you'll be discovering things about your world you never even considered. If you start a game with new players and decide you don't want witch hunters, you can pluck them out since they aren't "hard-coded" into the setting, only the previous game.
That's the beauty of a Fluid setting, it can be completely different depending on the group playing. It will always be fresh and new to the GM with each new group. You can keep what works and toss what doesn't.
Just remember:
If the players don't experience it in the game, it doesn't exist.