Request for Advice on Worldbuilding

I’m not normally the kind of gamemaster who does a lot of worldbuilding. I prefer to let the players determine their network of relationships and play through the drama of how the situation changes those relationships.

But for Fallout, one of the things that always excites me is the environmental storytelling, exploration, and humor, and I haven’t practiced running or prepping those things very much.

I know that it uses the Commonwealth setting from Fallout 4. I never played that one, but half of my potential players all have so I want to set it somewhere else. Preferably somewhere that the Fallout universe hasn’t covered very much.

I ended up picking Texas, specifically near the Gulf Coast. The Big Thicket down to Houston. I know that Fallout: Brotherhood of Steel takes place in Texas but, for context, Carbon is 300 miles away from Houston. Boston is only about 480 miles from Washington D.C., so plenty of space to do my own thing.

Also, from what I understand, nobody likes FBoS so I’m good.

Anyway, I’m essentially working with a huge empty canvas and it’s very intimidating. What advice do y’all have for coming up with my own Fallout material, tips for worldbuilding, and/or pitfalls to avoid?

A lot of it depends on what type of game you’re putting together, a sandbox game takes more front loaded world building than something more adventure/quest based. If you’re going primarily adventure based or have good reason why the PCs can’t just hike 200 miles west to see what’s there, then you really only need to flesh out the local area. Some places of interest, some Fallout things - Super Duper Mart, Red Rockets etc. Maybe rumors of a vault somewhere nearby. Add in some raider games and some factions and before long you’ve got a strong framework to build on.

I find I get a lot of mileage out of using Google Maps so I have an idea what real world things are in the area and then either turn them into wreckage or make them Fallout-y. A Coca-Cola bottling plant becomes a Nuka Cola plant, a car plant becomes a General Robotics factory, a National Guard Outpost becomes a BoS camp etc.


This is great advice, I’ve already started brainstorming how to alter some of the stuff that I know about Houston and Texas to make it more Fallout. For instance, Dr Pepper started in Plano, TX, and it’s available everywhere. I can picture cargo cults who trade in, I dunno, “Dr Power” Cola bottlecaps instead of Nuka Cola, of there being an exchange rate, that sort of thing.

I was also recently made aware that the vast majority of Houston’s port trade is oil/gas related, and that there are 10 oil refineries within the Houston metro. There’s so much there for me to work with.

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So apparently Houston is also a major medical tech hub. I’m imagining Vault-Tec pharmaceutical and bio research departments and partners being all over the area. Especially in the Big Thicket.

The area is probably seeded with all sorts of Vault-Tec and competitor life sciences labs. Between that and all of the mutating effects of magical Fallout radiation, it’s probably a pangaean nightmare world.


Also look for any well known local cryptids. Not necessarily big name ones like Bigfoot but most communities, states, provinces have local legends.


San Antonio also has a big Med Tech industry.

The port of Houston may be mostly Oil/ NG in our timeline but in the FO timeline that would have gone away. No telling what it was replaced with.

Same applies to the oil refinery. They may have sat unused for decades before the war. However they may make for good fortified settlements. Best of all they are far enough from city center, plus not in active use, that they probably did not get nuked. The huge storage tanks may also make good settlements.

Interesting fact about oil wells. Most last 10-15 years at high production then rapidly decline in output. However they can still produce for decades after that. There could very well be a oil well still producing a dozen barrels per day 200 years later.


Ah see, I didn’t realize that oil started to actually go away. I assume you’d still need oil for plastics even if oil as an energy source was unnecessary.

The oil wells thing is fascinating, and it reminds me of Waterworld, of all things.

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When I world build in any game one of the first things I do is build the map. For Fallout I brainstormed some locations, checked to make sure I wasn’t stepping on canon too much (I’m okay with doing some), and then did some thinking about how I would change the location.

I decided go with Providence. I then looked at the map and thought about what fresh hell I can unleash on it, and I decided that a large portion of the bay front areas would be 50ft underwater. I haven’t decided what the mechanism is, but that’s not critical for me. I then printed a Google maps sheet and penciled in the new coast line.

Now that I have my rough map and defining geography, I started to think about what the impact of a sunken city would have on how people lived and behaved- from a Fallout POV*. Who would settle where, and how would they interact? What is the tone of the various sections, and how does it treat outsiders?

I take all these scribbled notes and then start to think about what kind of campaign it’s going to be. What is going to be the underlying thread that eventually connects the quests, and when will side quests contribute to that?

From that I loom at how that may change what I wrote previously about the location. How do I need to shift things?

After that the time consuming part starts. I’m not writing a whole source book that others will read, but I want to put my thoughts and ideas into a cohesive document to cement them in my head, and allow me to look back to get ideas.

Now it’s time for NPCs. I only do a few ahead of time. These are people important to a district. Mayors, gang leaders, military figures, traders, and maybe religious leaders. They help serve as a seed for story making. Other NPCs I prefer to form organically as the players interact with them. It just makes for more memorable “people” inhabiting the world.

The final part of world building for me is making final maps of the area and districts. Having a real city as a guide helps this a ton. Knowing distances helps me run a game, and seeing the maps helps players get into the setting.

After that I start making the first adventure. Having the world defined helps make that alot quicker.

Side note: One of the things that some players stumble on in test sessions was the fact that they are fixated on what the Commonwealth was like in the video game, and fail to realize that some shortcuts you have to make in that medium that do not have to be present in a TTRPG. The one I hit was how video games have to squish space. In Fallout 4 Concord has a total of maybe 15 buildings, and is a 5 minute walk from Lexington. When I pulled out some more close to reality numbers they were a bit confused why it took longer. The Fallout Commonwealth diverges from ours in many ways but setting thr scope was important to me.

Anyway, that’s my process. I enjoy it.

*Fallout, like most post apoc entertainment, takes a pretty grim view on humanity’s ability to reform functioning cities. I try to not let my own humble education on such things get in the way of fun games, so I keep things as “Fallout” as possible.


This was very thorough, thanks for writing it all out.

Something I’ve decided to do is actually pull out Microscope by Lame Mage Productions. It’s a group-based method of generating a history that works great as a sort of session 0.5 for RPG campaigns. I figure since I don’t know much about Fallout lore and I’ll be playing with some players who are like me and some who know a lot more, everybody can introduce elements that they like and by the end of a session we’ll all have some degree of emotional investment and understanding of the setting.

Also, I was reading the National Park Service’s page on amphibians and reptiles and it says that alligators are secretive and don’t interact with humans much, which makes me want to make intelligent mutated croc people who are shy and try to stay away from humans, but something’s disturbing their territory and pushing them towards the city.

It isn’t that oil was unnecessary, it was scarce.

A major part of the lore is the Resource Wars, when oil started running out. It’s what pushed the development of fusion power for everything.

The lack of oil also explains why you do not see a lot of plastic in game (plus the 50’s aesthetic).

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For the sunken city.

A bomb created a huge crater in the bay and fractured the surrounding rock. The entire city has been slowly drifting down into the crater.

An earthquake cause a large section of the city tilt into the ocean. There may be a cliff or water filled gap at the fault line.

For the settlements it depends on what types of buildings are common. Two, three and four story buildings will be under water. High rise buildings, that did not collapse, would be the most likely places to live. Pontoon or even rope bridges would connect some buildings. Maybe the side of a toppled building serves as a dock/ ramp. Gardens on roof tops. Water level floors are fortified or simply filled in to keep out Mirelurks.

Some raiders may rely on small fast boats to catch travelers or fishermen. Another has a barge with a crane and boarding ramps.

“Fallout, like most post apoc entertainment, takes a pretty grim view on humanity’s ability to reform functioning cities.”

They say that a loss of 30% of the population would cause society to collapse. This is largely due to losses being asymmetrical. People tend to work near where they live. Localized events (in a major city) could take out basic services like power or water. Truckers could be taken out by disease, in turn cutting food and repair parts supply.

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Ah, got it. I assumed that there would have been a significantly larger push for more oil early on the Fallout timeline resulting in more petroleum processing infrastructure. I knew that oil scarcity was part of the explanation behind the Great War, I just didn’t know how quickly things happened.

Short term collapse, perhaps. 200 years later? No.
Cities would form long before that. Books exist. Family groups banding together is a natural human tendency. If you look at existing sociological research on the subject they say that people are just as likely to band together and chip in durring a major population collapse as they are to give in to brutal tribal chaos.

As for my world building… I have ideas. Leaning into sunken horror ideas, as well as the shark dolphins we see in FO4, as well as glowing ferals climbing out of the dark water. Oh, and Mirelurks of course. The Dead City also will be ruled by Elder Gods cultists.

My Providence will have had the bay side districts built up so ther will be buildings rising from the sea. Bridges, gates.

And all that is just one district.

Considering Texa’s oil past, they will probably be a hefty Poseidon Energy presence there. Planning to play in Texas too, I’ve started t othink about the kind of facilities they might have left behind.

One of them i plan to place in the Permian Bassin area : the HEORP site (High Energy Oil Recovery Project) - basically, fracking with nukes instead of high-pressure water. Could be a start for a ‘fun’ location (and probably a little bit radioactive…)

If you allow vaulter characters, obviously you’ll need vaults - check the fallout wikis for unnassigned vault number first. And define by numbers a rough sketch of what happened there after the War. Including if they were ‘normal’ or experimental vaults along with what kind of experiment went there and what kind of effect it left on the locals. Depending on your players, you may use player input for that too

As an example, i have one which wasn’t experimental but used for Austin’s high and mighty - which formed the core of the current Texas government (of course not of all Texas, no matter what they might whish or say). The result is that a Vaulter form it is basically a pampered dilettante who’s likely to have serious trouble managing the harsh outer world…

One additional resource that I’ve been using is Snazzy Maps. I found links to some Fallout styles.

This will allow uou to use Google maps to develop your regions


You may be on to something with HERO Project.

Fracking uses conventional explosives to fracture the rock, the fluid transmits the force over a larger area and carries the small particles into the cracks formed. This makes the rock more porous and allows the oil to flow better.

Mini nukes are about the right size for sending down a drill hole.

I suspect the difference in oil production between this and the Falllout world is due to their delay in electronics and computers. Much of oil exploration is done by analyzing data from seismic and radar surveys. if I’m not mistaken gasoline was still available just prior to the bombs falling, just very expensive. It’s possible one of the refineries was still in operation. The others were likely shut down but still intact.

Houston is also a major manufacturing center for the oil industry and there are several forges in the state. With the reduction in oil well being drilled (world wide) that makes for a lot of excess production capacity. Fortunately there was a war going on and some oilfield equipment is on the same scale as tank turrets. There could easily be a couple hundred machine shops in the area ranging in size from a few thousand sqft to F###n huge. (I know of one company that their largest building is 10 acres). The shops are also spread out all over the city.

San Antonio also has a large military history. At one point they had 4-5 Air Force bases and 2 Army bases.

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There was a D20 Fallout game that lost the Fallout rights before it was released. I believe they re-branded as Exodus. They had a Texas sourcebook. No idea as to the quality or whether it would be helpful for you but I suspect you could mine it for ideas.

I actually have the exodus book. It was pretty good for running fallout back in the day

Try and get 2nd hand copies of either Sprawl Sites for Shadowrun or Critical Locations for d20 Modern… neither games were post-Apocalyptic but will cut down on map making for reference/combat encounters. I’ve used a few of the maps from Sprawl Sites in my FFG Star Wars games - the hotel rooms, casino/bar etc…

There’s also a load of free downloadable genric street tiles for various ‘Road Warrior’ games like Car Wars:


The biggest question you should ask is what kind of story do you want to tell, and that should inform some of your design decisions. Who are the major factions? Do you want to use the same ones from the video game, create your own, or mix and match some from both columns? What are the major conflicts in the area? How and why do the PCs get involved?

My setting is the Pacific Northwest. Because of the tech revolution in Seattle, that’s the main base of a group of hostile synths. Western Washington is contested by the Fort Lewis division, which is an outgrowth of the army base outside of Tacoma. There’s also the anachronistic group of Samurais who draw their inspiration from old B movies and books (which likely contained wildly inaccurate information). The tri-cities of central Washington are near the Hanford nuclear plant, which obviously melted down during the war and caused frogs to mutate into a crudely intelligent warlike group. Spokane was nuked because of the Fairchild Air Force Base, so the main downtown area is still badly radioactive. Lake City is where Couer d’Alene Idaho is now, was founded by the Fort Lewis Division, and is contested by the Samurai.

And then there are the elements of the region I’d rather not talk about because I don’t want to spoil it for my players or for the people watching my Pacific Northwest game stream.

The other piece of advice I can offer is to leave yourself plenty of room to be creative as you go. If everything in an area is rigidly defined, it becomes a chore to shoehorn new elements into it.

Also, that Snazzy Maps suggestion is a good one. I’ve made use of it.

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