The Sewers of Haven: A Guest Blog from Our Dungeon Crafter
Well met, weary traveler!
My name is Thomas Sitch, and I have had the pleasure of working on some of the new content rolling out in Dungeons Deep. If this is your first visit, Dungeons Deep is built on human authored adventures run by an AI Game Master: real tabletop RPG play with dice, character sheets, maps, and combat, solo or with your friends.
I'm one of the people who author the adventures you play, and this blog post goes over our newest area. Without further ado, I give you: the Sewers of Haven.
Last updated: August 21, 2026
From Graph Paper to AI-Core
This process has been a creative's dream, allowing me to put many of my old-school Dungeon Master skills to work and combine them with the cutting-edge AI-Core aspects of Dungeons Deep. The process begins with brainstorming: what are the areas of the dungeon? What factions are in them? Who are the NPCs who want to help you, and who are the NPCs who will probably fight you?
As you can see here, my dungeon crafting also included totally old-school graph paper maps (truly, these make my heart happy).
Then the work is laying out each room in the dungeon and connecting the maze of different chambers together, not unlike what I do on my game table at home.
If you'd like to hear me ramble about this process at greater length (and I do ramble, I love this stuff), here's a look behind the curtain:
Balancing the Encounters
As with my weekly Pathfinder game, I have to sit and think hard about the balance of monsters, how many fights are present, how high the CR is for each encounter, and so forth. Once that's all in place, I run some statistical evaluations to make sure that players aren't going to feel underchallenged, or worse, suffer a TPK when they try to explore the area.
New NPCs, New Quests
Finally, integrating the sewers meant building new NPCs and new quests. For example, the Cobblesalvage Market is an underground bazaar, built in an ancient dry cistern, where a community called the Cobbles keeps the peace.
Part of both the technical and creative side of this design is setting the "triggers," the various secret knowledge and motivations the NPCs have. Your Dungeons Deep AI Game Master can then take those quirks, knowledge, and motivations in-game to give you hours of interaction and the hunt for secret lore.
This is one of the most gratifying parts of world building in Dungeons Deep. It's like making a toy, sprinkling magic dust on it, and watching it spring to life.
At the core, as with a tabletop game, is the writing. I get to take ideas and spin them to life, and enter those ideas as first-class citizens in the game. If you're like me, backstory matters. I want every monster, every trap, and every puzzle to have a reason for being there. Ideally, I want those to encourage the player to ask new questions and lead to new quests.
The dungeon is deep. Never stop exploring!
Lore: The Underbelly of Haven
A City's Cast-Off Bones
Beneath the crumbling streets of Haven lies the Underbelly: a vast network of sewers and cisterns raised in a wealthier age, when a real river ran through the town and caravans crowded every road for miles. That prosperity is long gone. The river has dwindled to a dry bed of cracked silt, the upper quarters stand half-empty with their doors swinging on corroded hinges, and the tunnels below have been left to rot right along with them. What was once a civic marvel is now a lightless warren claimed by outcasts, brigands, and a troubling number of the restless dead.
The Working Sewers
The uppermost channels were once the pride of Haven's engineers. Without a river to flush them clean, they have choked on decades of silt and debris, and wherever the passages beneath the town's abandoned quarters no longer serve their original purpose, something has usually moved in to claim the space: armed squatters, quiet predators, and a few things stranger still. Newcomers rarely go far before someone takes their measure. Not everyone down here means harm; a canny few make their living selling the one thing worth more than coin in the dark: knowing which way is safe.
Deeper Still: The Cistern and the Cobbles
Push in far enough and the brickwork gives way to something older: a vast, bone-dry cistern that predates Haven itself, and beyond it the Cobblesalvage Market, built into a natural cavern of dripping stone. Here the Cobbles, a resourceful community of patchwork folk stitched together from every people that ever passed through Haven, keep neutral ground where surface folk and stranger travelers from the deep places below meet to trade in salvage, secrets, and, if you know where to ask, genuine magic. It is the one true refuge in the Underbelly: a hot meal, a cup of something that glows faintly in the dark, honest goods mended out of dead Haven, and a proprietor or two worth staying on the good side of.
Territory Best Left Alone
Wander off the beaten path, though, and you may find ground no one should walk lightly: flooded channels claimed by a secretive clan of wererats, and the Hungry Quarter, where some old and malignant working keeps the dead from ever quite staying dead. And rumor has it the sewers aren't the bottom. Older stonework is said to wait in the dark beneath them: sealed doors, forgotten names, and something down there that has never once needed to introduce itself.
Some of what lives down there, you'll want to see before it sees you. Turn the wrong corner in the sewers and this is what's waiting:
And not everything in the flooded tunnels means you harm. Meet Lorch. That's all I'll say.
Questions for Thomas
How does an AI Game Master run a hand-designed dungeon differently from a generated one?
Every detail is built carefully and provided intentionally by the human designer. That way, the AI Game Master can't "flub" and give away secret details that have not been uncovered. We're not dumping text files in a chat bot. We're very intentionally designing layers of content that the AI Game Master discovers and reveals to players.
I have a favorite trick that I do in my tabletop games. I will hand a player an envelope at the beginning of the session. That envelope says "open when told." The player knows NOTHING about its contents until they are told to open it. Then, when it happens, there is something cool and very specific to that player's character. Were they replaced by a doppelganger? Had a sudden vision? Remembered critical knowledge about a long-ruined keep?
The way we build the story into the AI Game Master is much the same way. The AI Game Master has a giant set of "envelopes" that are not to be opened until the right time. It works very well for AI-Core campaigns.
Do I need a party to explore the Sewers of Haven, or can I play solo?
You want a full party, starting at level 3, with good character balance. There are a lot of tough fights down there.
Will there be more content below the sewers?
Yes! There is a necropolis hidden below even the sewers and cisterns. Ancient things sleep there...
What did you learn at your home Pathfinder table that made it into this dungeon?
Lorch is inspired by my wife's dice box she bought at PAX :)
Who's your favorite NPC in the Cobblesalvage Market?
That's hard, because the Cobblesalvage NPCs are some of the most interesting and colorful I've worked with. I like Tilda Scump best, I think. She's a human-presenting wererat, who is fundamentally a good soul: she wants to serve people food, and she works all kinds of angles to get vaguely fresh ingredients and such to her hot pots. She is always worried about the other wererats coming back to kill her, and so she carries a small crab Figurine of Wondrous Power in case things ever go sideways.
The Sewers of Haven are rolling out now. Jump into Dungeons Deep and see how deep the Underbelly goes.
This work includes material from the System Reference Document 5.2 (“SRD 5.2”) by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.