Working with the Design Space of a Tabletop RPG’s Resolution System

I want to make decisions about the main resolution system for a game I’m designing, but feel stymied because I don’t know what the relevant design space is. I don’t feel confident that I know the questions I can usefully ask. You can see  a similar problem (while designing a different game) in my previous posts Combining Dungeon World attribute checks with LotFP skills, badly, and in Some numbers for Dungeon World rolls with LotFP skills — I’m coming up with ideas, and generating some stats about them, but I don’t have any clear idea of my goals so it’s all a bit aimless.

I want to know:

  • What is the space of plausibly-useful resolution systems that I can use for a game like the one I am designing?
  • How can I “navigate” that space for a particular game so as to home in on the system that gaves me game behaviour I like?

A definition of “resolution system”

A resolution system is a subsystem of an rpg that resolves character success at some task or conflict.

Illustration by examples of resolution —

  • Rolling your Burning Wheel skill dice vs an Obstacle value
  • Rolling d20+your attribute mod+(maybe your proficiency bonus) vs a DC in 5e
  • Rolling d100 vs your skill percentage in a BRP game like Call of Cthulhu

There are of course many assumptions embedded in the above, and the examples show that I am thinking in a particular design space (albeit one in which the majority of popular games fit).

A beginning of a game design

I am designing a game1 provisionally called The Edge of the Forest. It’s a fantasy game where the PCs are protectors of a small settlement on the edge of civilisation. To narrow down the design space I am interested in, I will state some facts about the game that I’m taking as axiomatic for now. You will probably find them very ordinary.

  • The game uses a universal resolution mechanic, whereby the vast majority of rolls in the game are of one type
    • In this respect, it is more like Burning Wheel than any D&D, and within D&D more like 3e or 5e than 1e or OD&D
  • Resolutions are required when the GM deems that a character is attempting something where both success and failure are both possible and interesting, or where they are opposed by another character (PC or NPC)
    • This is roughly the Burning Wheel rule for when rolls are required
  • Resolutions are at least partly random
  • The results of resolution will at least be success or failure at the task (or a victory for one of the two contestants
  • Character attributes will change over time, based on something like experience

I have no plans to be innovative, certainly not in my resolution mechanic. I want to build the game I want, with little regard to whether it is truly new

One very broad question

“Given the above, what is the best resolution system for this game?”

If we break that down a little, we get things like “What dice, what numbers? How should those dice and numbers change over time (short and long term)?”

One very broad answer

“It depends. What do you want the game to be like in play?”

That’s helpful, especially to a novice who doesn’t know that it’s the stock answer to every broad design question. Were I a complete novice, you might have turned a question I drew a blank on into one I could at least form an answer to. Have twenty-six upvotes and two heart symbols.

But even armed with that I am still likely rather stuck. I don’t know how to usefully decompose that question. I am likely to form some answer, but will it cover everything that I need? Will it even contain anything actionable?

To address those concerns, I think we need to understand the design space of this resolution system, or at least the interest parts of it.

The obvious, tangible descriptions of the design spaces are mostly noise

When describing the design space here, there are some traps to fall into. You might start by saying something like:

  • Roll + add vs difficulty
  • Roll-under
  • Dice pool versus difficulty

Or, indeed:

  • d6
  • d10
  • d20

But I think those are mostly noise. They are the physical realisation of resolution mechanics, not the mechanics themselves. They have aesthetic and guilt-by-association effects on the game experience, but those are not the most important part of that experience. Article like this one on the rpgsite are not wrong, but they are not about the most important things.

For certain target audiences, die preferences are very strong. See Monte Cook’s notes on why he chose the d20 for Numenera (link may be dead — his brief summary is “In short, I created a system using a d20 mainly because of the affection and identification gamers have with it.” (source). But I think most people are actually flexible in this. And I’m sure that everyone would benefit from being flexible in this.

The interesting axes of the design space are quite abstract

They are things like

  • The possible outcomes
    • Types of outcome include:
      • Failure at stated task
      • Success at stated taks
      • And… (criticals and fumbles)
      • But… (partial successes and complications)
      • Control of largely-colour narration
        • e.g. Burning Wheel’s main “success in a task” example has the GM asking the player to “Describe it for us, please!” (BW Gold, p30)
      • Control of substantive narrative
        • Inspectres is an extreme example here
  • The probablities of getting those outcomes
  • The effects of those outcomes
    • Mechanically
    • In the fiction
  • What classes of activities are there (i.e. what different things are that characters can try to do)
    • e.g. combat, verbal argument, crafting, exploring …
  • The disparity in results between and greatest expert and a a total novice person (and every point in between)
    • … in each of the activity classes
  • The outcomes when experts and novices (and every point in between) conflict
    • … in each of the activity classes
    • (in most widely-played games, the answers here differ a lot by activity classes. But they don’t have to — see HeroQuest, or Burning Wheel played hub-and-spokes only)
  • How much general ability (e.g. a “technical” attribute) matters, compared to specific ability (e.g. a “starship engineering” skill)
  • The way in which equipment and other clearly external-to-the-character aids are represented in resolution
    • As modifiers under certain conditions
    • A special abilities that change the rules
  • Are PCs and NPCs approximately symmetrical (e.g. as in BRP games, World of Darkness), or are different models used for them (e.g. Numenera, PBtA games)

We can guide ourselves to explore the design space for our designs by asking the right questions

Questions like:

  • How competent do you want the PCs to feel?
  • What advancement arc do you want PCs to go through?
    • Zero to superhero (most D&D), journeyman to master (Burning Wheel with a 4 lifepath start), superhero to slightly different superhero (Spirit of the Century).
  • How much do you want equipment, and other character-external things that are held in some way by characters, to matter?

Answering them does not design our resolution system, but it gives us some requirements to design towards. And I think they may help to “crack the stone”; they may provide “entry points” into a design, and help you when you’re stuck.

I don’t see these primarily as quality checks, in the way that the Big 3 and the Power 19 are. They’re more akin to the lenses in Schell’s book on game design.

Where next?

Having an explicit expression of the relevant design space won’t design this resolution system for me, but would would provide a space in which to do that design. In extremis, we could develop something like a “resolution design pattern catalogue” — something that maps desired properties of a resolution system to specific kinds of resolution mechanics and the tools (like dice and cards) that implement them. But that’s rather beyond the one design I’m concerned with here.

Given the start above, we can expand our model of the design space and the set of questions for use in exploring it.

We could also collect examples of different answers to the questions in the form of specific games and concrete mechanics (I have provided a few above, but I’m sure more will be useful).

Finally, we can collect advice and patterns for analysing systems in terms of the design space model. E.g. what graphs and statistics are good to use to check that your success rates by expertise level are indeed those that you want?


1. I am in fact designing several games. Who isn’t?

3 thoughts on “Working with the Design Space of a Tabletop RPG’s Resolution System

  1. I would ask: which other subsystems do you want to tie into what you call your “resolution” system?

    For example, you mentioned “Character attributes will change over time, based on something like experience”: this could go one way, like in several flavors or D&D (the higher level you are, the greater your success chance) or two ways, like in some Runequest/BRP-based games (when you successfully employ a skill, mark it for a chance to improve that skill during downtime).

    Or, you ask: “How much do you want equipment, and other character-external things that are held in some way by characters, to matter?” I would also ask how many such things do you want to matter. At a minimum, the more factors you want to have, the bigger the numbers you want to use, because of granularity. But the number of factors you have depends on the number of related activities you want to have in the game. Say you want to include a weapon-crafting subsystem where non-magical weapons of varying degrees of quality can be made, and you also have different types of magical weapons on top of that: then you need room in your resolution system for differences between all those classes of weapons.

  2. Rafu — I’m not sure whether “want to” is right… it feels like these decisions are more likely to be things you are forced into by other goals and desires. But certainly your top-level question is a good one to ask.

  3. There is some good discussion of this post at ( and storygames (

    For now, I’m going to leave this as-is while I think about this particular design some more, and play some more games in its rough space.

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