D&D 5E - Mapping a fantasy kingdom - sizes and scale
There are two responses I have to this, which hopefully should (imo) lead to less irkage on your part: One, developing the larger world and understanding the context and influences on the "game region" can bring a better sense of internal consistency and coherency to the game. I've played in many games in which the DM didn't really take the time to develop the world, and it always felt like we were moving in a moving game-stage, which paper-thin set-pieces. Players who prefer a more "gamist" approach don't mind this, but those (such as myself) who enjoy story and immersion into a secondary world find it, well, irking. This is not to say that a DM must spend years building a world before starting the campaign, but that some forethought and planning, and continued development really can bring the world alive.Two, and perhaps most importantly, because world building is fun in its own right, aside from role-playing. I agree with you insofar as one is building a setting for a campaign, but some DMs, even many, build their worlds for the pure creative pleasure of it, in addition to making it a workable setting for a game.
But yeah, as far as newbie advice on world building for a campaign--and back to the OP--if we're talking relatively straight-forward fantasy with roughly Medieval technology level, a small kingdom is a good place to start. You really only need a small area detailed to begin with, then as the game progresses the DM can gradually develop the rest of the world. But I would also recommend to the thread starter that in addition to creating the "starter kingdom," consider any ways in which your world is different from our own. Number of moons? Climate? And general questions: what's the overall technological level? If you have a map that the campaign is going to be focused on for awhile, you don't need to know all the details of places off the map, but a general idea is good - because you also want to have a sense of neighboring lands, influences, etc.
Also, as far as the size of the starting area go, I would suggest taking 20-25 miles/day as a good rule of thumb as how far one can travel in a day on relatively even terrain. You could travel further, but if you're navigating hills, mountains, or marshes, then it will be a good deal slower. So really we're talking about anything from 5-10 miles for rough terrain and poor weather to 25-40 miles for flat terrain and pleasant conditions, or more on horse or if pressed (e.g. Aragorn, Gimli, and Legolas in the beginnng of The Two Towers when they were going after Merry and Pippin were, I imagine, traveling 50+ miles a day; you also have ultra-marathon runners capable of 100 miles within a 24 hour period. Of course this isn't sustainable over many days).
Then I would think in terms of your starting point, and consider a radius of a week to 10 days from that. 10 days x 25 miles = 500 miles, so a map of 500 x 500 miles should be plenty big to start. That's roughly the size of France. Actually, I would consider drawing two maps to start: one, a larger regional/kingdom map ("France") and secondly a smaller map of the local area, maybe 100 x 100 miles. As I mentioned above, at some point it wouldn't hurt--and could be quite fun--to sketch out a larger world map at some point, with the understanding that most of it you'll never use and you're mainly doing it for your own enjoyment.
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