I’ve attempted twice to build a completely custom world, with varying degrees of success each time. Here are some tips (by learning the hard way):
Things I learned from worldbuilding:
- Don’t stick with a “Pangea” map (that is, only 1 big continent). It prevents easy “shipboard” encounters (unless PCs happen to be on a coastline), and requires other natural barriers like mountains and forests to divide nations. It’s also more difficult to add premade adventures using a “previously undiscovered island” or some such, because an island would have to be off the usual direction of travel instead of close to a “usual water travel route”.
- It’s easier to draw nations if you have natural barriers to their borders, such as water or mountains. Forests can work, but forests can also be cut down or burnt, which could change your territorial lines!
- Think trade: all nations will seek out trade of some kind, and will use rivers as passage. Your nations will be heavily affected by their access to trade, and it will in turn affect prices and availability of goods in that area, even to the point of using different coinage (steel instead of gold, for example).
- Don’t forget passes in your mountains. Passes are almost always controlled or guarded by someone or something.
- Most mountains should be preceded by at least a few hills.
- Don’t make your initial continents too big. You can always add continents later, but too many at the start just gives too much travel area, and forces you to focus on “macro” details, when you need to focus more on details that players care about.
- Do have a mix of places that various races can originate. There’s nothing worse than having a gnome character who doesn’t have a homeland, because you never bothered to make one. Try to have multiple possibilities for each race, even if some of those races have small villages mixed in with human settlements. You should have these named and located before a campaign begins, so that PC backgrounds can reference them – but you can let the player’s imagination flesh out the nature of those settlements.
- Don’t forget the evil humanoid races. They usually won’t all live underground! Races like Giants, Hobgoblins, and Orcs often have large strongholds in desolate or behind near-impassable terrain.
- It’s good to have some areas of “wild lands” or unsettled regions. Try to assign some major geographic landmarks to these areas (mountaintops, rivers, craters, etc) so that you can refer to them later when you need a place for something special to reside or be found.
- Nations of the same race should still be quite different. Don’t make all your dwarves the same, nor all your humans the same. Use things like “available resources” and differences in habitation / climate to shape different peoples. That is, one race might be horsemen or nomads because of the grassy plains they live on (and abundance of horses and/or herds to hunt), while jungle people may never have seen a riding animal, but are fantastic trappers and foragers, have access to rare herbs, and have powerful shaman.
- Mining towns are quite different from milling/farming, or fishing towns, even within the same nation. They affect the types of people that live there, and what goods are available and at what prices.
- Decide how magic affects daily life in each settlement or nation. The availability of magic affects its cost, and will heavily influence living conditions – druids can boost crops and populations; an abundance of clerics affects political structure and may result in theocratic governments, and abundant wizards could produce automations or services, affecting everything from streetlamps to security.
- The abundance of magic heavily affects the balance between the magic-using classes and the weapon-using classes. I ran a “low-magic” campaign which resulted in every PC multi-classing into a class that used magic, because magic was so powerful compared to (non-magical) weapon use. Fighter-types, and rogues especially, NEED magic-item support in order to contribute effectively to the party after about level 6-8. This limitation of the D20 system is one reason why the “Level 6 cap” has been implemented by some groups.