4 Hours w/RSD - Introducing Undermountain (Ryan Dancey)

The past six columns I’ve been laying the groundwork to talk about my own personal home game and why I think it will be interesting to the people reading this column. I haven’t played in a tabletop RPG group since I stopped living full time in the Seattle area about 10 years ago. During the time I’ve been gone I’ve played a handful of pickup one-shot games and played in several convention...

The past six columns I’ve been laying the groundwork to talk about my own personal home game and why I think it will be interesting to the people reading this column.

I haven’t played in a tabletop RPG group since I stopped living full time in the Seattle area about 10 years ago. During the time I’ve been gone I’ve played a handful of pickup one-shot games and played in several convention games but haven’t had a regular scheduled gaming night. That’s changing this week.


I’ve spent the past week or so creating my home game system that I call “Undermountain”. Actually it would be more fair to say I spent a week writing down the ideas I’ve had about how I’d like my game to work – most of the mental labor has been done in idle moments over the past several years.

The pitch is simple: Your characters are members of a unique adventurer’s guild / inn / general store that has an artifact that lets parties be transported into a virtually infinite underground environment (The Ruins of Undermountain) filled with puzzles, monsters, traps, and loot.

It happens to be set in the big fantasy city of Absalom on Golarion, the home of the Pathfinder tabletop RPG, but you won’t be spending much (if any) time in the city. The game is focused on dungeon crawling. It is designed to do some very specific things, all related to packing more fun into our 4-hour game session.

  • The game is derived from Pathfinder, which I consider the most robust implementation of the kind of game I want to play.
  • The game is designed to be quick and easy for new players to understand and for people who have played any version of D&D or AD&D to be able to grasp very quickly.
  • The game is built around the Open Game Table philosophy of encouraging drop in players, people who attend irregularly, and newbies unsure about this whole tabletop RPG thing as well as regular players who expect to play every week.
  • It is a testbed for ideas I’m working on for my current project in the MMO space where I earn my living these days. I can prototype and test concepts that I might want to explore more fully in the digital realm without having to worry about the complexities of getting software and graphic assets actually created to my specifications.

Let me discuss each of these things in detail.

Derived from Pathfinder

It would be fair to say that Undermountain is to Pathfinder what Chess is to Advanced Squad Leader. The more complex game is designed around the idea that highly experienced people willing to invest tremendous amounts of time can create a unique and special experience that is detailed, realistic, packed with choices, and customizable to a wide range of scenarios.

Like Chess, Undermountain is a much simpler game that tries to do just a few things but do them very well, while providing an environment that is “easy to learn, hard to master” – or rather “easy to learn, rewarding to master”.

The design goals for Undermountain were as follows:

  • Standard Pathfinder character archetypes
  • Standard D20 3.x mechanics
  • A focus on “dungeon” style adventures
  • Limits to character movement and knowledge
  • Characters who could solo but work in more interesting ways in groups
  • Easy access to D20 support content (monsters, spells & magic items most significantly)

The Pathfinder core rulebook is 576 pages. It includes essentially everything you need to play a highly detailed, very complicated, extremely well tested game from the day a character is created as a 1st level nobody through to that character being a 20th level demigod plane-traveling Übermensch. You get spells, magic items, classes, prestige classes, and encyclopedic lists of Feats. The only thing you don’t get is a catalog of monsters; but never fear, Paizo provides you with not one, not two, but soon to be three huge collections of monstrous creatures for your game. If you put all the Pathfinder core books together, you’re looking at something like 2,000 pages of content (to say nothing of the extensive line of Golarion Campaign support material and Pathfinder Society scenarios).

Undermountain does not exist as a printed book. It is designed to live as a wiki, a hypertext, user editable document hosted on a website. Wikis do have pages, and Undermountain currently clocks in at 46 pages. Some of which contain about a paragraph of text. And it (like the Pathfinder Core Rulebook) doesn’t yet have any monsters in it.

It cannot possibly do what Pathfinder does, but what it can do is create a hugely fun experience based around moderately powerful player characters exploring a dungeon, fighting monsters, solving puzzles, exploring, gaining phat loot, and powering up.

Undermountain doesn’t have to contain all those pages of data and rules because it can simplify a Pathfinder rule, and then link to the Pathfinder source in the event that the simplified version of the rule needs help. I don’t expect to have to consult the game’s “Big Brother” very often, but knowing that we can removes a lot of concerns about the robustness of the game system.

Since Pathfinder iterates on the D&D 3.0 and 3.5 game systems, it provides a lot of very well tested basic mechanics that are easily leveraged. When you strip out the special cases and just use the core rules systems, you get something that is fairly lightweight and easy to understand. I didn’t have to invent bonus types, or conditions, or any of a myriad of other things that my game needs – I just use them as Pathfinder uses them, just with less text.

Quick And Easy To Understand

There’s really good research that shows that humans actually gain less enjoyment from having lots of choices than from having fewer. D20 gave players so many choices that it overwhelms many people. They just can’t figure out where to start or what tradeoffs they’re making, or how to get all the materials put together in a way that gives them the kind of experience they want.

Undermountain tries to avoid this problem by giving people very streamlined choices.

Character Creation

When you create a character, you pick a race, an alignment, and 5 class levels. Then you do a little bit of customizing of those classes, and then you buy equipment from a very limited list of options.

All of these sub-systems are designed to present very easy to identify choices. You can’t really end up with a bad character unless you purposefully do dumb things (like give a melee fighting character a really bad Strength – and the rules even tell you not to do that and why).

Along the way I cut out a lot of options and choices.

You get a lot fewer choices of race. In fact there are just 5: Humans, Elves, Dwarves, Half-Orcs, and Ophidians. Ophidians are snake-people. They exist for the handful of players who want to play something really alien, and I expect them to be played quite rarely. Racial choices do just two things: They give you one bonus to an ability and one penalty to an ability; and they give you a simple racial power.

I really altered the alignment system. Instead of a logical two axis system like that in D20, I provide the players with arbitrary alignments appropriate to a dungeon crawling campaign derived from my observation of hundreds of players over dozens of years. In Undermountain, your alignment choices are Good, Chaotic, Scoundrel, and Badass. I probably don’t even need to explain what those mean. (There are additional NPC and monster alignments: Evil, Alien, Domination, Hive and None).

You can’t play a Bard, Barbarian or a Druid in Undermountain. There is no Monk class but there is a simple way to customize the Warrior class to make a Monk character (without 20 levels of individual special powers).

You don’t have to pick skills. You don’t have to pick Feats (but you do get 5 points you can spend on modifying your classes according to a few simple rules and a short list of options).

Other than calculating how much your chosen armor and weapons cost after you enhance them, buying your starting gear is extremely simple.

It takes about 5 minutes for an experienced person to make a character from scratch, and most of that time is spent writing, not making decisions. I expect it will take about 20-30 minutes for someone who has never played a tabletop RPG before, and somewhere in the middle for inexperienced players.


Spells are one of the things that really slows D20 down. The spell lists are so huge and the rules determining who can cast what spells and how often and how they work and how they interact with all sorts of subsystems are incredibly opaque.

Undermountain chops those rules down to nearly nothing. There are two kinds of spells in Undermountain currently – Low Level and Medium Level. They are derived from the 1-3rd level Pathfinder spells and the 4-5th level Pathfinder spells. The only spells in Undermountain are simple, easy to understand effects. You can’t travel through walls, into other planes, or from point to point. You can’t see or hear information unless you’re physically present. You can’t summon other creatures. You can’t modify your own, your companions’ or your opponent’s ability scores.

Each spellcasting class (there are 3) does a very specific thing:

  • Clerics heal and remove negative conditions like sickness (and they are good fighters and can still destroy undead)
  • Sorcerers help control the battlespace and make other characters more effective, and solve problems that can’t be solved by brute force
  • Wizards deliver lots of damage and lots of synergistic effects for melee combat characters

The other thing that is interesting about the Undermountain spell system is how often you cast spells. You cast them a lot. Basically, I want the players playing spellcasters to stop worrying about spells as a resource – just like fighters don’t think about melee attacks as a resource. Between hit points, potions, food, and time, they’ve got enough pressure pushing the adventure forward without asking the players to stop so their characters can sleep every 30 minutes of realtime.

There are 21 low level Cleric, 20 medium level Cleric, 14 low level Sorcerer, 15 medium level Sorcerer, 10 low level Wizard and 7 medium level Wizard spells. And that’s more than enough to do virtually everything I need spellcasters to do in Undermountain.


The biggest simplification to combat is the removal of Attacks of Opportunity. They’re just gone – nothing replaces them. That’s a huge amount of overhead that was generating very little in the realm of “fun” for most players.

There is also no reach weapon system (there is a weapon that acts like a reach weapon but its ability is codified into its description).

The elimination of the Feat system also massively reduces the complexity of the combat system. It’s reasonably easy for even a new player to figure out what kinds of things he or she could do at any point in a fight, and what the likely best course of action is.

My goal is to take combat down to a level of simplicity where I can give a new player a short 10 minute tutorial, and then they can fight their character without help and do a reasonably good job (not the best possible job, and not the most creative job, but a reasonably effective job).

Leveraging Open Table Gaming

I travel a lot. Many of my gaming friends do too. It has always been a problem in keeping a regularly scheduled game running. The constant changes in character line-ups and the loss of continuity from session to session has frustrated me to no end.

Undermountain is designed to avoid those problems as much as possible.

The Session

Everything begins and ends in one 4-hour session. The characters all start in a place of relative safety. They get a briefing on where they’re going and what they’re going to be rewarded for doing. Then they go into Undermountain to play the game. At the end of the session they emerge (if they haven’t all died).

Most character resources are automatically replenished at the start of each session. Virtually nothing permanently affects characters from session to session except increases in class levels, and the gear they own. Characters level up every 4 game sessions.

Multi-session plots, such as they are, will be broken down into atomic units that can be resolved in one session. Players who have seen other bits of the plot may have a slight advantage, but nobody will be confused about what is happening or what the stakes are.

Characters Are Well Formed

It would be possible to run an Undermountain session with just one PC, or with a very large group. Because each character is basically guaranteed to be serviceable as an explorer and able to defend itself by itself the game won’t break down if a critical character is absent.

Undermountain Is Infinite

Likewise, the area of the session is essentially mutable to match the power and skill of the group who assemble for a session. The challenge level of the game can be configured so that it shouldn’t overwhelm the party, but also gives them plenty of options to wander off and get themselves into huge amounts of trouble.

If the group wants to play an extended session its very easy to keep the game going – there’s so much material already produced for Undermountain that I’ll never likely use it all, and if I wanted to I could easily spin in Monte Cook’s Ptolus, and AEG’s World’s Largest Dungeon too.

Testbed for Ideas

One of the biggest differences with standard D20 that I am testing in the Undermountain game is getting rid of the Will/Reflex/Fort save system. Instead, each ability score has a corresponding Resistance Roll. While this sounds more complicated than D20, I believe that it is actually far less complicated in the long run.

The classic system requires a lot of mental gymnastics if something doesn’t fit into the simple 3-part model. And that means that the game system has lots of special rules and subsystems to deal with the kinds of challenges that don’t fit into that system. Those kinds of rules proliferate and create huge headaches for players and GMs alike.

In Undermountain players and GMs can quickly see what Ability should be used to resolve a test. In fact, I have renamed two of them to make even more clear what they do. Wisdom has become Perception, and Constitution has become Fitness. Using this setup I was able to quickly convert all the spells and magic items from Pathfinder to Undermountain on the fly as I wrote their text into the wiki.

Another thing I’m testing is my injury system.

In Undermountain, you basically only die from a handful of things that usually involve the removal of your physical body from the game (like disintegration or falling into an underground river). When you reach 0 hit points you fall unconscious. You can be revived by getting your negative hit points removed taking you back to at least 1 hit point. And then you take an Injury. These are serious things that affect your character’s ability to act. You can remove them as well if you have help from someone with the proper abilities.

I actually do expect a lot of character death because Undermountain is a really dangerous place. I think the most common form of death will be a Total Party Kill. That’s ok, because making new characters is really quick. On the other hand, I don’t want to bog my game down with corpse runs, resurrection hassles and all the other stuff that typifies your average D20 game after the characters get access to advanced Clerical help. Players who do value their PCs, who have built them up over time, and want to keep advancing them will have an incentive to run away when the danger level becomes too great, and that’s a behavior I’d like to encourage. Hopefully the newbies will see and emulate this, as opposed to the “death is a minor inconvenience” play pattern I witness in many D20 games.

Both of these changes will be very easy to reverse if I don’t like how they work in the game. I see them as incremental improvements not revolutionary change.

Future Updates

The very first Undermountain game will be played this week. I’ll try to post some actual play reports in the comments following this article for those who are interested. I’ll also be writing more about Undermountain in the future, because I want to break down some of the choices I’ve made in more detail and explain the rationale behind them. So look for lots of interesting follow on content in the blogs to come.

--RSD / Atlanta, August 2011

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Ryan S. Dancey

Ryan S. Dancey

OGL Architect


Ryan, will we be given access to the Undermountain wiki at some point so that we can help break... er... I mean try out this latest innovation?

I think so. I just want to work on it for a few sessions and get real-world playtest experience before I start making it available to the public. I may want to try and commercialize parts of it too but I haven't quite figured out how to do that yet.

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First Post
Can i ramble on about a mediocre homebrew and get a front page article too?

Mod Note: While everyone is entitled to your own opinion about his work, we expect you all to be rather less rude about expressing it. Please, folks, try to make your criticism constructive. Thank you. ~Umbran
Last edited by a moderator:

I hate to say it, but this article was a complete waste of time. I (and others I'm sure) really don't care what kind of home brewed system you've working on. Why don't you keep this kind of <ahem> stuff in the forums where it belongs.


First Post

We are working on something very similiar for our gaming group, who also haven't played in quite some time. A couple key variations worth calling out:
1) We will be using a condition tracking chart, which will feel familiar but puts things into a better perspective.
2) We will be simplifying mulitple attacks.
3) We will be nerfing sneak attack, dual wielding, and haste effects.
4) We will be layering on a VERY SIMPLE "strategy" game which will feature a character's background, quirks, and motivation, while giving them the ability to interact with the story of the game.
5) Finally, we'll be pulling in the skill challenge system from 4e.

I am curious about how you plan to manage the balance component of the game that you're home-brewing? It seems QUITE different from out of the box Pathfinder in that your characters will be unable to cast better than a 5th level spell?


I am curious about how you plan to manage the balance component of the game that you're home-brewing? It seems QUITE different from out of the box Pathfinder in that your characters will be unable to cast better than a 5th level spell?

The game starts with 5th level PCs, so there's no need to worry about spells higher than 3rd level (they get access to some but they're not game breakers).

As the game progresses, they'll get access to more powerful magic, but it will still be scoped within the design objectives and won't break the game.

My "balance" criteria are:

1: Is it likely that each player will have something meaningful to do while exploring and while fighting

2: Is it likely that the players will find a challenge appropriate to their characters boring and easy to overcome

I don't really care that the Warrior could kick the Sorcerer's ass. It's not a dueling game. On the other hand, the characters are going to find places where having a Sorcerer in the party would be really useful, and the lack thereof will force them to back up and try to find another route.


Undermountain is part and parcel of the Forgotten Realms. I think you should find another name for it.

Secondly - this sounds very much like Descent or the WOTC D&D boardgames. More of a strategic/tactical boardgame experience rather than 'full-on' roleplaying. Seems strange to put in all this effort for an experience which could be achieved more satisfactorily in another gaming medium...


I hate to say it, but this article was a complete waste of time. I (and others I'm sure) really don't care what kind of home brewed system you've working on. Why don't you keep this kind of <ahem> stuff in the forums where it belongs.

I disagree. I am very interested in filleting the fat from PF/3.5 into something manageable for new players and have been trying to devise a way of doing many of things within a limited 'free time' window, so I for one am very anxious to read on this subject further.

I would play a game like this in a heartbeat, if for no reason than to not have to lug around every PF book to choose feats and still fight off the nintendo generation for not being 'optimal'.

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