Step 1 takes a couple hours. I start with a Geographical Map at a 1:10,000,000 scale or higher. Usually 1 map at that scale is enough, my worlds tend to be smaller than earth, even if there are a number of "continents."
Most of the time it looks like
Blue Marble Next Generation (Blue Marble 2004), but with colored pencils. I'll name some oceans, seas, mountain ranges, deserts, island chains, major rivers, etc. I'll name the continents. I'll draw out wind currents and indicate climate ranges (arid, temperate, sub-arctic, etc). I'll identify any major manifestations of magic that are related to the land itself.
It doesn't have to look like a professional map, and you don't have to waste a bunch of time thinking about how you want the landmasses to be shaped. These things form randomly, just make a circle, oval, or rectangle on a sheet of paper and draw squiggly lines in it. Then erase stuff that you don't like. It shouldn't take long. I use 1 sheet of 8.5 x 11 inch paper, sometimes front and back. Usually I draw a
Robinson Projection (an oval map).
I know it sounds like a lot, but it isn't. Just draw stuff, the players will like it regardless. No one ever,
ever says something like "Wow, your continents are really well formed," or "That's a stupid place for a sea, what were you thinking?!" I mean unless you have a geophysicist in your group.
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Step 2 also takes a couple hours. I trace the outline of the continents and land masses on another sheet of paper and draw the Political Map. Use some of your major geographic/geologic/oceanographic/etc features as borders and contested borders. There's no real reason to have more than a couple dozen countries
max, your players might actually visit something like 10 kingdoms/countries ever in a very long campaign. Decide on the cultures/races of the major countries, which countries have major conflicts and
where those conflicts take place regionally. Draw out some major trade routes. Decide which countries form alliances together and which are part of larger empires.
Mark in some capitol cities and other major civilized destinations. Make some ancient ruins. Decide where technology is at, where art and music are flourishing, where are the major sites of worship or physical manifestations or marks of the deities (if any). This is the map showing things that have *impacted* your world, rather than just its geography. But again, just like the geographic map, don't think too hard. Just drop things down...force yourself to draw lines even if your brain objects for "reasons." Ignore your brain, just draw random countries and stuff.
Use random name generators to make random names for places. Seriously. Maybe name a handful of places yourself if you're really attached to certain names, but otherwise ain't nobody got time for that. There's a lot more things to name on your Political Map than on your Geographic one.
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Step 3 also takes a couple hours. Build a couple closer up region//city maps of the area the players start in, maybe with some roads and a few towns//villages.
A couple maps. Not ten, or twelve, or whatever. Unless you have multiple days//weeks to spend on this, don't try to go all out. These maps should be usable for actual play for the first several sessions of your game.
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Steps 1 through 3 take a Saturday or a Sunday — maybe a Saturday plus a Sunday tops. But these maps can last you for years, and you can play
multiple campaigns on them. When your players want to a explore a new place in your world it's going to be
so much easier to get them there, narrate them through their traveling experiences on the way, and build a couple new region maps for the new place when they arrive.
I'm telling you right now, that the way miss_bun has approached world building is the same reason that she fails at it when it spirals out of control.
Don't try to design a Forest by starting at the Trees.
Zoom out, and start at the top. Start at the view looking down on your world from space. Draw that. Make that...it doesn't take long. It doesn't have to be detailed. Worry about that later.
All you're doing is building a mesh outline, basically, of the world. You'll fill in places with more detail later. And you'll be thankful you already have that outline in place.
You can hammer out entire worlds in a day. Just start from above.