New Project: 5e Procedural Megadungeon

This is a bad idea.

Let’s start with that. Get that right out of the way, intercept the comments, and set everyone’s expectations where they should be. Actually, let’s emphasize.


Right now, we can….

Hold on, I don’t like the defeatist tone there. Let’s try once more.

THIS IS (probably) A BAD IDEA!!

Nailed it.

So yeah, the idea is in the title, so you may have an idea of what I’m talking about already. But for people who don’t start their day with sites like, you may need some definitions.


A megadungeon is a D&D adventure site that has a particular style of play attached to it. First, it’s big. There is no end to the dungeon (or the end is very far away). Second, the goal is to go in and come back out alive, possibly laden with treasure. So there is a village or base camp or something that the heroes return to, recharge and trade treasure for tools to go back in. Third, a lot of the game is more resource management, than it is of say, roleplaying. There is a bit of the roleplay, but a megadungeon is an adventure for the players, not the characters. Fourth, while the megadungeon is rather lethal in general, it gets more an more dangerous the further down you go.

D&D started with a megadungeon. Gary Gygax had his Castle Greyhawk that was his home campaign, where characters descended into a zaney place where “A wizard did it” was a standard explanation.

Procedural is another word I through up there, which basically means I don’t front load the work like I’ve poked at in other things. Some things that occur, the layout of the structure, for example, is a surprise to me as it is to the players. Also, the monsters they fight are rolled up on a table, as opposed to being keyed to specific locations, like they are in normal dungeons.

Procedural content can theoretically be infinite, although it also has a chance to repeat. Minecraft and No Man’s Sky are two procedurally generated games.

5e, of course, refers to Dungeons and Dragons Fifth Edition, the system I play the most of, distinct for, in general, being a bad system for doing games based on lighting, encumbrance, and resources, all of which are standard Megadungeon fair.


Good question, heading! And a hard one to answer. I don’t have a solid straightforward answer. I have pieces of answers. First, I have wanted to do a megadungeon for a while. 13th age has a pretty amazing sounding one called Eyes of the Stone Thief. I keep coming across people playing various deep delves and I’ve always thought I’d love to do one.

They’re a commitment, however. If I bought one, I would probably be looking at $50, for a game that would likely need to be converted into 5e, poorly, that no one would want to play. Such is my lot. So I haven’t bought a thing for it, yet. (Or did I?? More on this later)

Also, my online game has been faltering of late. The thing about a megadungeon is the number of players can swing wildly. Heck, as long as I set careful boundaries, I could run a character through next to the party to pad their numbers! Megadungeons support people coming into the middle of the game, with no need to explain backstory. In fact, once the dungeon has been built, you can use the same maps for an all new party. There were just adventurers who had gone before. Maybe they were nice and solved some devious traps for you. Maybe they were unlucky and there is a corpse and all that loot just sitting there in room 8 for you. Who knows?

The procedural part is hand in hand with the price concerns of the previous paragraph (as valid as they are, considering I occasionally buy RPG manuals I’ll never use in play…) I don’t want to spend forever building a clever dungeon, only to never actually use it. I’ve gotten better at running moderately compelling encounters from chance on a table with my ToA excursions. This would help me get even better at it.

And 5e of course, for a slew of reasons. First, most of the advice I see online for megadungeons are specked for D&D, including things for previous editions. Numbers might need tweaked, but the thematics are the same for the editions. Second, I am very familiar with it and have a lot of tools, as well as a confidence on how to go off the books. Third, it is an edition that is very close to its core content. If I decree a race or feat removed, nothing collapse. If i need to invent a new type of proficiency or skill, it’s easy.

Fourth, my players have a general knowledge of the game. I don’t have to try to get people to do a bunch of homework or teach a new game at the table. Maybe in the future I could do some of that, but for now, making the entry effort as minimal as possible is very useful.

And fifth, Xanthar’s came with some very handy tables that I spent all morning thinking about and pouring over and may have done 1/3rd of the work on this project for me, straight up.


I still need to polish a few of the exact way I am doing things, but basically, beneath a town I need to name, there is some massive, sprawling, dangerous megadungeon. There may be a small starting quest, but the game is basically to delve in and get out, repeatedly.

The dungeon itself will be somewhat generated on the fly. I might do the first or second… rings? rows? Okay, so when they go down, they hit the first room, with its doors. Then behind those doors are rooms and corridors. That’s the first… line. Each location of the first line has the potential for some doors and such. Behind those is the second… wave… of locations. There is a good word for this concept. I know it. But for the life of me, I have no idea what it is at the moment.

Anyway, I would likely roll up the first two… ranks… of map, then, as the party ventures in, I would use dead time when I can spare the cognitive load to build in the direction they head, so there is always at least two… horizons… beyond where they are. Ideally, I shouldn’t have to stop play to add maps and stuff. But nothing in the dungeon should be planned so far ahead that the cool stuff I add in will never be seen. (The ability to add in whatever magical/trap/encounter whatever I think up as the game progresses and build the dungeon around new concepts is really exciting.)

Of course, the dungeon isn’t empty. I have an interesting little random encounter table, kindly provided by Mr. Xanathar, which gives me a large amount of monsters to draw on, some of which can be fought, others which should probably be talked to.

And then I’ll need to figure out traps and treasure and maybe throw some thought into making the town come alive a little. So there is still some work for me to do, but, basically, once I figure out how I want to generate the dungeon, I hop in roll20 and dedicate a map to the town, and a map for each floor of the dungeon. Or make some paths that connect, so Floor 3 might have a West and an East, things like that. Fill the R20, reuse as much as I can week to week, profit.


This will probably be something I’ll start doing with my online group. We’ve had too many weeks where we would have had only two people at the session. With the Megadungeon project, we would have been able to play those weeks.

Also: this might extend opportunity for me to run a second table with the same table. No confirmation on that, but I do know there are people who want to play who are not able to make the Tuesday. I don’t want to pick up a third (kind of a fourth or fifth, actually) table, because I don’t want to have to keep track of all those stories, the information I’ve dropped and so on. But if I can have 2 of those table basically plotless and set up so work I do on one is also immediately useful for the second, that would be amazing.


This is the question, really. I might be able to get things ready by this week. It really depends on if I decide to do D&D work, or other work, or leisure reading tommorrow.

I also do need to assemble a briefing document, with just a bit of information about changes I know will be happening to the game. It shouldn’t be a long document, but it would be needed before people make characters, which puts an urgent spin on it. If I had that in your hands by Monday morning, who would be ready for a game Tuesday night?


-we sign off for now. I tried to continue the thing, but meh. This will be online, as that will be easiest to convey the information, keep it around, and make sure things aren’t forgotten. But actual details will be forthcoming. (I might start writing some of it now.

This project has my fire for the moment, which is always fun. We’ll see how long the fire lasts and if we can get some good games out of it. Or learn why they aren’t great. Either is fine.


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