Having populated the urban centres of your setting, you now have a world to fill with monsters, travelling rogues, nefarious cults and the odd planar entity.
At this point, you should have a world and a handful of places. It’s time to get a map. Draw one, find one, ask a friend to make one for you. Whichever you choose, a map will help you keep track of things. This is mostly true for fantasy campaigns, but I feel that if you’re playing a game set in a real place having a map can enhance the atmosphere.
Regardless, after somehow getting a map, you should put your urban centres on it. With that done, you should realise that there are large areas of empty space. Most of this space will likely never be explored. Some of it can be filled with new urban centres but the rest….. the rest is where you get to make your setting come to life.
If you’ve been following these guides, you should already have a rough idea of what lives where. If you haven’t been reading these articles, that’s fine. The main purpose of this article is to expand upon my advice from Roleplaying 105 that “[w]hen populating the world, the people and monsters living there should make sense.”
I feel that I cannot repeat this enough. Nothing that you control will break the immersion of the game more than the player characters coming across a monster or an NPC that is so incongruously out of place that there is no reason for them to be there.
I’m not saying you can’t have creatures and NPCs in odd places, just make sure to have a good reason why they’re there, and do not it too often. Sure, finding an Ifrit from the Plane of Fire living at the polar ice-cap might lead to an interesting quest-line (maybe it was captured by a powerful wizard who seeks to harness its power and open a portal to the Planes) but the more of these oddities the players encounter, the less they’ll pay attention to the ‘normal’ things.
Which isn’t a good thing because a) it detracts from the importance of the oddities and b) if the events surrounding the characters are of a more normal nature (relatively speaking, of course), there is a higher chance of the players themselves becoming invested in what’s happening.
While, again, I’m offering brushstrokes guidelines rather than explicitly detailed rules, it’s worth splitting the map into different terrain features. Work out where each area of terrain ends and the next begins, work out what the prevailing weather is for that area. You might even want to divide an area of terrain up and have two goblin tribes with different cultures occupy a small range of hills.
At the end of the day, you should have a good idea of what the geography and climate of each area roughly looks like, even if it’s just a sentence or two. With this knowledge, you can throw some monsters into the mix. There are lists in books and online that arranges monster lists by environment, don’t feel ashamed or scared to use those.
More importantly, don’t fill the area in detail. As a rule of thumb, know what two or three creatures the player characters are likely to encounter. If they go somewhere and you need more creatures, look at those lists. If you don’t have those lists handy, ask for a short break and look at what monsters you have available. If there are any that fit, throw them into the mix, if not, are there any you can adapt to suit your purposes?
Much like all the other advice in these articles so far, keep it general enough that you have the most flexibility without being unprepared, but detailed enough that the players don’t realise you haven’t accounted for every possibility. You can plan as much as you want, but if the players never go somewhere, you’ve wasted time that could be spent honing the plot they’re following. Alternatively, if you do plan everything in great detail, you can repurpose the inhabitants of one area for another.
If you are to take anything away from reading this, I suppose it is that whilst you should have a general idea of everything, it’s worth delving slightly further into detailing the areas the PCs are likely to visit next, even if it’s just for your peace of mind.
This applies for NPCs as well. Adventurers are likely to meet other people on the road, or in tiny little places you’re forced to invent on the spot. If you know roughly the type of person who would live/be travelling in each area, you’re more likely to feel comfortable with this level of improvisation and your players will feel immersed in the world because, as far as they know, they’re meeting people who have existed in this area since before their characters started adventuring.
Really, as with most things in life, the rule of KISS applies here. Keep It Simple, Stupid. And honestly? You can make everything as detailed as you want, plan for every contingency, populate every dungeon, and the players will still throw a spanner in the works.