How much of your world do you need to prepare ahead of time to make the world appear fresh to your players?
Let’s avoid the obvious extremes of zero preparation on the one hand, and a binder full of notes on the other. Some people run successfully with one extreme or the other; this post is not for them. This post assumes that, if you personally invent a secret society during your game session, it’ll work, but it’ll feel made-up to the players, so you want to avoid that.
We’ll start with a principle: The most important elements of a world relate to people and geography, and how they conflict.
You don’t need to define every country in your world ahead of time. You only need the current country and its neighbors.
For each country, you need to define each country’s conflicts with each other. So, what do countries conflict get into conflict over? Two main things: boundary disputes (usually resulting from previous invasions) and trade.
Boundary disputes imply prior military conflicts between these countries. You just need to write down what land is in dispute and a reason for now. The reason usually has to do with an imbalance of trade or resources; a strip of land that’s particularly fertile, or defensible, or indefensible. It could even be religious. This will help to define each country’s geography, too.
Defining the trade differences is a big help to your world-building, because that defines a few of each country’s major exports and imports. This will also tell you what professions will pop up most commonly in these countries.
One helpful way to think of conflicts between countries is answering the question: Why aren’t these countries at war yet? Pretend that war is inevitable between any two given countries, and ask A) why each country would go to war with another, and B) what’s prevented it from breaking out so far.
You’ll want to define representatives of three broad categories of people: governmental, religious, and popular. There may be some overlap, and that’s fine.
For governmental people, I include hereditary rulers, elected officials, and even the military: anyone with major organized power. Who are the big movers and shakers? Who could start a war?
Role-players tend to shy away from religious elements in their games. That’s a shame, because religion provides some of the most interesting story fodder. Who are the major religious leaders in each country (or across multiple countries)? What religions or factions do they lead? Note that many influential religious leaders direct relatively small cults of followers, and they may be known more for their politics or activism than for the number of their followers.
Popular people lead informal groups, from school founders to martial arts masters to philanthropists to investors to major merchants. For this, you need each person’s name, the name of the organization they lead, and a reason why they’re particularly popular.
Define at least two characters in each of these three categories. To define a character, I mean give them each a name, a simple personality trait, at least one connection to one other character (it can be a character that you haven’t defined yet), and the group(s) to which that character belongs (parliament, court, military, school, guild, religion, etc.).
You’re not quite done with people yet. Also name five other characters, and give each a simple personality trait. These will remain available to you for improvisation.
Fantasy adventure requires one more significant detail:
What monsters commonly inhabit each country? For each monster, rough out a single prototypical enclave or encounter. You just need a rough map, location of creatures, and pointers to stats. The key here is to define a prototypical encounter, the kind that frightened townsfolk gossip about in the tavern. Stat that out and have it available in your notes.
Anything I’ve missed? Let me know in the comments.