A System for Creating Dungeons During Play

What’s the Big Idea?

Most systems for creating Dungeons are designed to be used by the GM, before the game starts.  First the GM creates the Dungeon, and then, when game time comes, the PCs explore it.

This system works differently.  In this system, the Dungeon is created as the PCs experience it – not before.  It’s primarily designed for collaborative, GM-less play, but if you’re a traditional GM, you can also use it to generate Dungeons on the fly during play, if you’re willing to improvise a little.

Right – on to the system!

The Three Characteristics of Dungeons

In this system, all Dungeons are rated by Peril (as are Adventures, Journeys, and so on, if you’re using those components of the larger system).

All Dungeons also have the following three characteristics:

  1. Dungeon Type (Cavern, Mine, Ruin, Tomb etc)
  2. Dungeon Theme (Haunted, Infested, etc)
  3. Monster Ecology (Aberrations, Goo, Undead, etc)

The third characteristic – Monster Ecology – has three “slots” for Monsters: these are the Primary, Secondary and Tertiary Monster Types.  The Primary Monster Type is the type of monster that most commonly frequents the dungeon, the Secondary Monster Type is a bit less common, and the Tertiary Monster Type a bit less common again.  Just to keep things interesting, this system also has various entirely random monsters showing up now and again, and also allows for monsters from the local Region wandering into the Dungeon from time to time.  That ought to keep the PCs on their toes.


Laying the Foundation:

What The PCs Already Know About the Dungeon

When the PCs first hear about the Dungeon, they probably won’t know very much about it – but they’ll know something!  Some examples:

  • The PCs they might hear of an old ruin and decide to go exploring it, but not yet know what state it’s currently in, or who now lives there.  Gnolls?  Bugbears?  A dragon?
  • The PCs might have vowed to stop the Orcs who have been raiding the local farms – but they might not yet know exactly what kind of Dungeon those orcs are using as a base.  An old mine?  A ruin?  A cavern?

And so on.

To start creating the Dungeon in play, begin by nominating a Peril rating

Then roll for just one further piece of information about the Dungeon – either:

This represents what the PCs already know.  Don’t determine anything else just yet!   To find out more, you’ll have to ask around, do some research – or simply go there and begin exploring.

You now have a single piece of information about the Dungeon.  As the characters find out more, that single piece of information will be the foundation upon which the rest of the Dungeon is built.

(Note: if you’re using the full System for Creating Fantasy Adventures on this site, then your PCs may already know something about the Dungeon.  If so, don’t roll – simply use that information as the foundation, and move onto the next step: Researching the Dungeon! )

Researching the Dungeon

It’s sensible to find out as much as you can about the dungeon before you enter it.  f you have time before setting out, you might want to Research the Dungeon.

Journeying to the Dungeon

Once you’ve finished your research – or if you just want to depart right away – you can use my System for Running Fantasy Journeys to make the journey to the Dungeon interesting, if you like.  This can be an adventure in itself!

Arriving at the Dungeon

When you finally reach the Dungeon, you might be quite surprised by what you find. It may be more Perilous than you’d been led to believe – or just quite different to what you expected.  Roll on the table below.

So, What’s This Dungeon Really Like?

Roll 3d6.  (Need a die roller?)  Modifiers: +4 penalty if anyone critically failed their research roll.  Research re-rolls can be used on this table.

3-5 This Dungeon is not as dangerous as you’d feared – and there’s more loot! (-1 Peril, but +1 Peril for treasure purposes)
6-7 There’s better pickings here than you expected (+1 Peril for treasure purposes)
8-11 This Dungeon is pretty much precisely what you expected.
12-13 This Dungeon is a bit more dangerous than you signed on for – though also more lucrative! (+1 Peril)
14 This Dungeon is quite different to what you expected. Roll for (1-3) a new Dungeon Type or (4-6) a new Dungeon Theme.
15-16 This Dungeon is significantly more dangerous than you’d been led to believe – but also more lucrative! (+2 Peril)
17+ This Dungeon is utterly different to what you expected. Roll for a new Dungeon Type and Dungeon Theme.

This is also the moment at which those with skills like Naturalist and Tracking can do a little research of their own, to try to work out what’s really going on. This occurs after the roll on the table above.  Critical failures on Naturalist, Tracking, or similar lead to another roll on the table above, with at +4 penalty!

Entrances to the Dungeon

You always know of at least one entrance to the dungeon – otherwise there would be no adventure! But that entrance may be concealed, difficult to reach – or worse.   To determine what that entrance is like, roll on the table below:

Dungeon Entrances Table

Roll 3d6.  (Need a die roller?)   Subtract 2 if the dungeon is in constant use (a cave that serves as the base for Orc raiding parties, for instance). Add 2 if the dungeon is abandoned or sealed (e.g. a forgotten temple or an ancient tomb). Research re-rolls can be used.

The entrance is…

3 or less …wide open.

4-5         …very problematic indeed. It is concealed as per entry 11; guarded as per entry 8-10; and locked as per entry 12.

6-7          …possibly guarded?  To tell, check Observation at a penalty equal to Peril. Each attempt costs 1 unit of time. If you succeed, roll 1d6. On a 1-3, it’s clear. On a 4+, it’s guarded: proceed to entry 8-10 on this table. A critical success means you’re able to enter when no guards are present. Failure gleans information: you’ll have to decide whether or not to risk it, and if you do, you’ll have to make a roll halfway through your approach to determine whether or not it’s guarded. On a critical failure, the whole party is surprised by the guards!

8-10        …obviously guarded.  Roll up a standard encounter’s worth of monsters.

11            …concealed.  To find it, roll against Perception at a penalty equal to (N+Peril). Each attempt costs 1 unit of time.

12           …locked.  To unlock it, roll against Lockpicking at a penalty equal to Peril – or break down the gate!

13            …possibly structurally unsound? To check, roll against Architecture, Geology, or similar, at a penalty equal to Peril. Success means you can roll to determine the truth right away. Roll 1d6; on a 4+ the entrance is unsafe or unstable; proceed to entry 15 on this table. Critical Success means you find a way to enter safely regardless.   Failure gleans no information: you’ll have to decide whether or not to risk it, and if you do, you’ll have to make a roll halfway through your approach to determine whether or not it’s unsafe. Critical Failure means that the entrance is definitely dangerous, and everyone takes a -2 on their attempts to enter safely. See entry 15.

14           …difficult to reach. To enter safely, roll against Acrobatics, Climbing or similar, at a penalty equal to Peril. Success brings you safely across; critical success finds a safe route for the whole party. Failure means a fall of 1dxPeril yards onto a hard surface. Critical Failure brings another member of the party down with you. The first person who makes it across safely can secure a rope, tap in Pitons, point out the best handholds, or similar: this is worth +3 to the rolls of those following.

15         …definitely structurally unsound. To enter safely, roll against the better of DX, Perception, DX-based Architecture or DX-based Geology, each at a penalty equal to Peril. Failure means taking 1d+(Peril) crushing damage; Critical Failure causes a collapse that seals the entrance shut – possibly with some of the party inside!

16-17      …very problematic indeed. It is concealed as per entry 11, difficult to reach as per entry 14, and structurally unsound as per entry 15 – as well as locked as per entry 12, for good measure.

18+       …wide open.

Finding Another Way In

If the first entrance looks a bit hard to manage, the players might want to find another entrance. To do so, spent a full unit of time and make a per-based roll against a suitable skill, with a penalty equal to peril. (Suitable skills include Architecture for most buildings; Mining, for mines; Hidden Lore (Magical Sites) for mystical ruins; Theology or Religious Ritual for temples, and so on).

Success reveals an additional entrance – roll for its characteristics as above. Critical Success lets you find an entrance closer to your goal: if you use it to enter the dungeon, make your exploration rolls as if you had already passed through 1d6 additional dungeon areas.   Failure finds nothing. Critical Failure means falling prey to a trap!

Basic Procedures for Exploring the Dungeon

You’ve successfully entered the Dungeon. Now what? In a few pages, we’ll outline how to determine the nature of new Dungeon Areas, as the characters explore them. But first we need to cover a few basic ground rules:

  • The Goal you’re aiming for
  • Dungeon Areas
  • How Time works in the Dungeon
  • How Dungeon Levels work
  • What to do if the Dungeon ends up full of dead ends.
The Party’s Goal

When you first enter the dungeon, you must nominate a Goal. The party’s Goal is usually the object of their adventure: the person they’re trying to rescue, the artifact they’re trying to recover, or similar. But not always! The following are all valid Goals:

Valid Goals

  • The object of the adventure: the artifact you’re trying to recover, etc
  • The stairs down. If the party is only on a Peril 2 level of the Dungeon, and their quest object can only be found at a minimum Peril of 4, then they’ll want to nominate the stairs down as their Goal. If you find this Goal, roll as for “Level Change: Going Down”, later.
  • An exit from the dungeon. The players should nominate this if they want to get out of the dungeon, and for some reason they can’t backtrack. If you find this Goal, roll as for “Level Change: Going Up”, later.

The party’s Goal can be changed at any reasonable time.

Dungeon Areas

The inside of the Dungeon is broken up into somewhat abstract Dungeon Areas. Dungeon Areas are significantly bigger than a single room.   To give you an idea – depending on the Dungeon type, an area might be:

  • A suite of similar rooms
  • A series of caves of the same type, linked by tunnels
  • A large, central mineshaft and its various subsidiary shafts

And so on.  The point is that the PCs will be in one Area for quite a while, and that Area is identifiable as its own thing.  When they’re approaching a new Area, they know it, because their environment changes.  Of course, they might not know exactly what those changes mean… but that’s half the fun.

Time in the Dungeon

Every Dungeon Area you explore costs half an hour, plus any additional time spent resting, etc.   In the dungeon, every four hours counts as a unit of time – so every four hours you should mark off a Unit of Time on the Adventure Record sheet.

Each Area Explored: 30 minutes
One Unit of Time: 4 hours
Dungeon Levels

As is traditional, the Dungeon is broken up into Levels. Unless otherwise stated, the characters enter the Dungeon on the first level. As they go deeper into the Dungeon, the Dungeon gets more dangerous. For every level they reach beneath the first, increase Peril by one.

Running Out of Options

If you’ve explored everything you can, and you still haven’t found your Goal, don’t give up! You’ve obviously just gained access to the Dungeon through the wrong Entrance – go out and search for another entrance, as described above, and then re-enter the dungeon from there.

Exploring the Dungeon

This is the big one!

The PCs now stand just inside the Dungeon Entrance, peering into the unknown.  Who knows what wonders – and perils – lurk within!

What’s up ahead?  Whenever you’re about to enter a new Area of the Dungeon, follow these steps.  You’ll be following this process repeatedly, each time you enter a new Area, until you reach your Goal.  Don’t forget to map the Dungeon as you go!

A note on the web interface here.  I’ve embedded links to all the relevant tables, so you can just click through to the appropriate tables as required.  However, if you’d prefer just to have all the relevant tables on a single page, so you can scroll up and down as you see fit, then you want this page.  Use whichever of the two methods you find most convenient!

1 – Try to discern what’s up ahead.

(Roll on the What’s Up Ahead? Table).

 2 – Try to work out where each passage, path, or route might lead.

(For each route up ahead, roll on the Area Type Table, if appropriate.)

(This is also a great moment to pause and describe the scene.  Try to imagine exactly what it is about this new Area that makes it seem like this sort of Area, rather than a different sort.  Are there tracks?  Strange sounds?  A change in the stonework?   You get the idea.  This is a great time for a Detail Round, if you’re using that rule.)

 3 – Either move forward into one of those new areas…

(Proceed to step 4)

…or spend time investigating whether or not things are really what they seem.

(This takes ten minutes, and involves having one PC roll against an appropriate skill, at a penalty equal to Peril.  This is where your imagined details come into play!  Take a closer look at those tracks, with Tracking!  Was there it a change in the stonework that clued you into the nature of this new Area?  Maybe Architecture or Archaeology can confirm your suspicions…

The other characters may make complementary rolls, if they have appropriate skills. Success lets you make the following But Are Things Really What They Seem? roll now rather than at step 4, when it’s too late to back out. Critical success lets you make that roll in advance, and gives you a -2 bonus on it. Failure gives a+2 penalty on that roll; critical failure gives a +4.)

4 – Move forward into a new area. It’s too late to back out now!

(If you haven’t yet determined whether or not things are really as they seem, roll on the But Are Things Really What They Seem? table now.  At this point, the PCs are considered to be roughly half-way into the area, or otherwise committed to it in such a way that backing out would be time-consuming, difficult, and/or dangerous.  Whether the PCs decide to continue or not, they should now have to make the rolls under 5 and 6.)

5 –  Try to traverse the area safely – and hopefully with profit!

(Roll for Mishaps and Opportunities. Then deal with the results – Mishaps first, of course!  This ought to be a fun scene.  If the characters are stymied, halted, driven to flight, or killed by the Mishap, they don’t get to take advantage of the Opportunity.)

6 – Mark off half an hour. Reach the other side of the area. Try to discern what’s up ahead…

Reaching your Goal

When you reach the area that contains your Goal, you’re all set for the climax of the adventure: the Dungeon’s final challenge.  What that challenge is, exactly, will depend on the adventure in question.  Refer to the appropriate entry under Adventures!

In particularly, you might need to check for Plot Twists here…  See Adventures for this.

Also, the Goal chamber also always has a Large Hoard of Treasure, because that’s just the way these things work.

Leaving the Dungeon: Fast Forward!

Once you’ve reached your Goal, you should allow the whole party to exit the Dungeon without further trouble. Yes, this is totally unrealistic! But it’s much more fun that way.

To make this even more fun in play, go around the table and have everyone describe, very briefly, just one thing that happened, or that their character did, on the way out of the Dungeon. Once everyone has said something, you’re out! Fast-forwarding in this way makes the story run a lot more smoothly. Of course, you may still have to make a difficult Journey home…