Dungeon generation is one of my favorite parts of being a DM. Going from nothing to a finished dungeon is one of the most satisfying parts of the game. Done properly, designing a dungeon can be a great part of “Prep as Solo-Play.”

Everyone has their own process for designing dungeons from the ground up. Mine is based loosely on the BX rules along with a few things I personally enjoy.

I will soon link a dungeon designed using this method and explain what I was thinking through each step.

Step 1 – Concept Shopping

I have a list of ideas, vibes, mechanics, and themes for dungeons that I add to whenever inspiration strikes me. Here’s a sample from my list:

• Hell
• Poison
• Sludge
• Accursed
• Gilded
• Clockwork
• Balance
• Elevators
• Sneaking
• Eyes
• Separation
• Bridges
• Weight
• Outdoor Integration
• Mutation
• Time Limit
• Already Dead
• Hive
• Forced Resurrection
• Dead Monk’s Family Recipe
• Leyline Extraction
• Causeways
• Alarms
• Security Owls
• Spiral Map, Overlooking Center
• Inside the Mechanical Beast
• Backtracking
• Recontextualization via Tools
• Shortcut
• Vertical

When I sit down to design a dungeon, I pick about 10-20 things from this list that I think might be interesting for the dungeon and write them at the top of a piece of paper. I read them over and over to internalize the vibes I’m shooting for. I don’t worry too much that I include all of them, but whatever comes out as I work is good.

Step 2 – Monster Shopping

At this point, I decide what Level this dungeon will be. I tend to make lots of Level 1-5 dungeons or so. Remember that the Level of dungeon corresponds to the Level of the party it is intended for.

From here, I write out a list of ~6 monsters to put in the dungeon. I tend to roll on tables from the Moldy Basic book or from whatever Monster Manuals I find interesting. I have ~4 of them match the Level of the dungeon, with the other two being one or two levels above.

Whatever method you use to decide on your monsters, start thinking about how they might interact in a dungeon together. Pick one or two monsters to be the main inhabitants of the dungeon, then roll Number Appearing for all of them. For your main inhabitants, roll Number Appearing using the Lair numbers, and for the other monsters, roll using the regular numbers. At this point, you should start getting an idea of what they’re all doing in the dungeon.

Now, I will turn this list of monsters into a Wandering Monster Table. I put the strongest monsters at the bottom and include all the information I need to run the encounters.

For our example, if I am designing a Level 2 dungeon, 4 of the monsters will be 2 HD monsters, one will be 3 HD, and the last might be 4 HD. I’ve rolled/chosen the following monsters for the dungeon, along with their Number Appearing.

Here is an example from one of my other dungeons:

Roll	Creature Name	No. App.	HD	AC	ML	Attacks
1	Robber Fly	d6	1	14	8	Bite d8
2	Rock Baboon	d6	2	14	8	Club d6
3	Oil Beetle	d4	2	16	8	Bite d6, Special
4	Mannequin	2d6	2	12	5	Strangle d4
5	Carrion Crawler	d3	3	13	9	Paralysis x8
6	Ogre	d6	4	14	10	Club d10

Step 3 – Rough Layout

Now that a Monster table has been generated, it’s time to actually design the dungeon. I like to start by deciding on a rough number of rooms for the dungeon. I tend to add rooms as I go, so I like to start with 5-10 and go from there.

Now it’s time to outline a sort of flowchart for the dungeon. Then I sketch it out on dot paper to get an idea of how it will look. It is incredibly important to add plenty of choke points, decision trees, loops, secret passages, and objective rooms to make the dungeon layout interesting. I take inspiration from FPS games like CSGO and Valorant. After sketching it out, I tend to draw a Melan Diagram of the dungeon to check for these things. This point is where we work hard to ensure the dungeon has been thoroughly “Jaquaysed”.

At this point, I will often revise the layout of the rooms a bit, sketching it out a few times until I like how it looks. At this point, all the rooms are just numbered shapes. I have not figured out what each one will be like, but I may have a few ideas going as I sketch it out.

Step 4 – Stocking the Rooms

Now it’s time to start fleshing out what each room contains. I like to use the Dungeon Stocking Table from Moldy Basic with some slight changes, reflected here:

Roll	Contents	Description
1-2	Monster	Roll on the Encounter Table to determine which Monster inhabits the room and how many there are
3	Spoors	Roll on the Encounter Table to determine which Monster left the spoors
4	Trap	Either preventing passage through an area or guarding treasure
5	Special	Anything interactive that affects the dungeon experience
6	Empty*	May contain interesting items (like glass tubes) or things that communicate lore (like frescoes)

Roll once for each numbered area and mark down the results. Then roll on the following table for each room to determine whether there is treasure in the room or not:

Roll	Monster Room	Trap Room	Empty/Spoor Room
1	Yes	Yes	Yes
2	Yes	Yes	No
3	Yes	No	No
4-6	No	No	No

If a Monster Room is determined to have treasure, roll on the Treasure Type table given in the Monster Manual. Otherwise, roll on this table:

Level	Silver Pieces	Gold Pieces	Gems (d100x10gp)	Jewelry (3d6x100gp)	Magic Items
1	d6x100	50%: d6x10	5%: d6	2%: d6	2%: Any 1
2-3	d12x100	50%: d6x100	10%: d6	5%: d6	8%: Any 1
4-5	d6x1000	d6x200	20%: d6	10%: d6	10%: Any 1
6-7	d6x2000	d6x500	30%: d6	15%: d6	15%: Any 1
8-9	d6x5000	d6x1000	40%: d12	20%: d12	20%: Any 1

After rolling all this, you’ll know where all the monsters and whatnot are and how much total treasure there is. Now it’s a good idea to total up the treasure and write down where it all comes from. It should look something like this:

• Room 4 – 500sp, 400gp
• Room 6 (Guarded – White Ape) – 200sp, 200gp
• Room 7 (Guarded – Chimera)– 4000sp
• Room 9 (Guarded – Water Weirds) – 1200pp, 2 gems (950gp each), 5 jewelry (900gp each)
• Room 10 (Trapped) – 200sp, 3 jewelry (1000gp each), 1 Magic Item

Unguarded – 500sp, 400gp

Total – 4900sp, 600gp, 1200pp, 2 gems (1900gp), 8 jewelry (7500gp), 1 Magic Item

Grand Total – 22,490gp value, 1 Magic Item

Step 5 – Revisions

Now, it’s time to make revisions. You can shuffle the treasures, monsters, traps, etc. around as desired. If you want to put the Water Weirds in Room 8 instead, that’s totally fine. Maybe the Water Weirds are there guarding Room 9 where the treasure is, or maybe the treasure is in the bottom of the fountain where they live. In any case, you’ll start to get ideas about how to hide the treasure, what the monsters are doing, etc. Channel these ideas and start rearranging everything until you’ve got something that makes sense for your dungeon

At this point, you’ll probably have ideas for what your Traps and Specials can be. I recommend riddles, puzzles, keys that match specific locks, talking walls, etc. Really anything that sparks your imagination.

You’ll probably want to redraw your map at this point, based on the revisions. This will probably be your final design of the map. Now all that’s left is to key the dungeon

Step 6 – Keying the Dungeon

Now that you’ve got your revised map and ideas for everything, you’ll need to key the dungeon by writing room descriptions for each room.

I try to add a few sensory details for each room, descriptions of the walls, doors, smells, sounds, etc. to help with descriptions. It is especially important to add information whenever there is a fork in the road, helping the players to make some decision. For example, if a hallway branches left and right, don’t just say it goes left and right, tell them that you smell the stench of death wafting from the right and you hear clinking cutlery from the left. This makes the decisions more than just a coin toss.

Explain where everything is in the room and how it works, including traps, treasure, secrets, and anything else in that vein. For monsters, explain what they might be doing in that room. This typically is the most time-consuming part of the dungeon-designing process. As you do this, your ideas will come to life and continue to develop. Think of potential hooks to get the party in this dungeon and write them down.

After finishing the key to each room, do one final look over for the dungeon layout, make any final revisions, and your dungeon is complete!