Nerd Numbers: Terminal Outcomes

As a game nerd, there are a lot of interesting things to explore and enjoy about games. There are so many types of games and so many elements that go into a game’s design and development. Math and numbers are are one of those things that get explored, examined, brainstormed, evaluated and evolved an awful lot over the course of a game’s development. As someone who has the fortune to be both a game hobby enthusiast as well as a game designer, I look at numbers in a wide context.

When developing roleplaying games, one math & number concept that kept cropping up was the concept of Terminal Outcomes. Over the course of my 30+ years of roleplaying, I have never been satisfied with purely binary results. Pass / Fail is fine for college courses, but in my roleplaying games, a dynamic table with rich story and compelling narrative are just as important as anything else a system may offer. If the system only offers pass/fail, it falls to the GM or the players to go beyond those results, which can often feel arbitrary. Or perhaps skipped altogether.

eotediceWhen designing the dice pool system for Edge of the Empire, I had a lot of mathy things to consider. Fortunately, I had years of experience and feedback from the dice pool system I designed for Warhammer Fantasy Roleplay to use as a backdrop. One of the features of WFRP’s dice system I’m most pleased with is the vast number of terminal outcomes possible. This strongly influenced the way the Edge of the Empire dice were developed.

So what are terminal outcomes? And why would anyone besides me even care about them?

The concept is quite simple. Terminal outcomes are a measure of all the possible results a system can generate. If your game’s core resolution system is flipping one coin, there are two possible terminal outcomes: heads or tails. That’s it. That’s all there is to it.

This simple example is not far off from the pass/fail dynamic in a wide variety of popular roleplaying games over the years. For example, a system may rely on rolling one or more dice, then adding or subtracting various modifiers to come up with a final value. If that value equals or exceeds a task’s threshold, the task succeeds, otherwise it fails. This is an extremely simple example and well-used in games because it is tried and true and can be easy to calculate. No matter how many dice or modifiers are rolled, though, the framework for this system still has a limit of two terminal outcomes. Not that there is anything wrong with that… it’s a functional system that has stood the test of time for a reason.

However, if we introduce more thresholds, we can start to introduce more terminal outcomes. Taking the previous example, if you fail to achieve the task number by 10 or more, we might call that a “critical failure” while conversely, if you exceed the task number by 10 or more, we call that a “critical success.” Suddenly we’ve doubled the number of terminal outcomes from two to four. That’s great, but it’s important to note that all four terminal outcomes still measure one axis of resolution: success or failure. Critical success or critical failure offer higher magnitude levels of pass/fail, but all four outcomes are still tied to that concept.

I wanted to go beyond that. In order to do so, I started thinking of other axes of resolution that could be applied to a task or story element. Over decades of watching movies, reading novels, and playing my favorite games (er, I mean extensive research) it became apparent to me that epic stories don’t rely on simple pass/fail results. How boring would Lord of the Rings be if it all came down to a coin flip on whether or not Frodo destroyed the One Ring? No, there are myriad effects that influenced that outcome and numerous actions along the way. There were complications and obstacles encountered, as well as timely assistance and intervention. You could see these additional influences as additional axes of resolution.

With this mindset, it’s no longer solely based on pass/fail, but also a matter of what happens along the way. What else influences the task, or what other outcomes does the task generate? Some of these influences may be expected, others unexpected or chalked up to good or bad luck. Sometimes it’s the environment in which the task is taking place, or the other people involved in the scene.

I wanted to create a wide range of results that could lead to a number of different outcomes. To do that, I felt it was important to introduce several additional axes of resolution. I adopted an approach of creating a system with four axes of resolution, with several outcomes on each individual axis. Using Edge of the Empire as an example, we’re going to look at three of these axes. The fourth axis has to do with “origin” — or the source these effects come from (in EotE terms, which color dice show which symbol and which symbols are cancelled on which dice) which is slightly more complex.




The three axes we’ll be looking at are:

  1. Pass/Fail
  2. Advantage/Setback
  3. Critical Consequences

Axis 1: Pass/Fail

The Pass/Fail axis still carries a lot of weight, answering the fundamental question of “did I do the thing I set out to do?” Using the development of the Edge of the Empire dice as an example, all failures are equal in magnitude, but success can vary in magnitude depending on how well the player rolls. For our purposes, I’ll define three tiers of success — a “minor success” where the player produces the minimal possible result for a successful resolution. A “moderate” success is a higher yield success that may have a greater impact, such as inflicting more damage in combat. Finally, a “major” success is the highest possible yield for this axis, and represents a significant accomplishment.

So Axis 1 has 4 terminal outcomes:

  1. Fail
  2. Minor Success
  3. Moderate Success
  4. Major Success

Axis 2: Advantage/Setback

The next evaluation takes a look at any side effects or quirks that may occur along the way. This axis does not affect the success or failure of the resolution — that part is solely resolved using Axis 1. Rather, since few tasks occur in a vacuum with no external influences, this axis looks at how those other influences impact a task. In simplest terms, this refers to positive or negative consequences that modify Axis 1. Did you succeed so well that you gained an additional advantage? Or fail but still get something out of the attempt? Conversely, did you not only fail, but Epic Fail with additional horrible consequences? Or perhaps failed, but there’s still a silver lining of some sort.

This axis has mutually exclusive results. A task can have positive or negative side effects, but not both. And each type of effect can vary in magnitude. Again, we’ll use the minor / moderate / major labels to indicate the magnitude of these additional effects. The final potential outcome in Axis 2 is a “push” in which neither positive nor negative side effects occur. That means Axis 2 has 7 terminal outcomes.

  1. Minor Positive
  2. Moderate Positive
  3. Major Positive
  4. Minor Negative
  5. Moderate Negative
  6. Major Negative
  7. Push

Axis 3: Critical Consequences

The final axis of resolution looks at high-impact effects that can occur in addition to all the other results. These critical consequences do not impact pass/fail, and they differ from Axis 2 in two important ways. First, the results are not mutually exclusive — you can have a positive critical consequence and a negative critical consequence. Second, these terminal outcomes occur less often, so for our purposes they only have two measures of magnitude: moderate and major. Since these effects are so potent, “minor” doesn’t really apply.

Since these results do not cancel each other out, even when we remove the “minor” label, there are a lot of possible outcomes. There is still the possibility that these results do not appear in the resolution, which gives us another possible “push” outcome. Axis 3 has 9 terminal outcomes.

  1. Moderate Positive
  2. Major Positive
  3. Moderate Positive + Moderate Negative
  4. Moderate Positive + Major Negative
  5. Major Positive + Moderate Negative
  6. Major Positive + Major Negative
  7. Moderate Negative
  8. Major Negative
  9. Push

Yeah, Ok… So What?

Looking at the total number of possible terminal outcomes, there are tons of ways a single task could resolve. There are even more possible outcomes, since rather than discrete values I’ve lumped together ranges of values into minor / moderate / major results. Otherwise, if we measured each value individually Axis 2 would have closer to 15 to 17 terminal outcomes and Axis 3 potentially 13 to 15.

Think of these results as a big task resolution buffet. Choose one item from Axis 1, another item from Axis 2, and a final item from Axis 3. Those are the different possible outcome combinations. So taking Axis 1 (4 possible results), Axis 2 (7 possible results) and Axis 3 (9 possible results), the dice system for Edge of the Empire has the potential to deliver more than 250 Terminal Outcomes.

That’s a lot, with the potential to produce a different result on almost every roll. Heck, that means we could run a session with 5 PCs, in which each PC made 50 skill checks for the same task –and theoretically they could all get a different result on each attempt.

If you factor in that 4th axis I mentioned earlier (the Origin Axis, which looks at the various sources of the results from the other 3 Axes), then you get into the thousands of possible results.

That’s pretty exciting to me as a designer, creating a way to offer a huge variety of outcomes within what I think is still a pretty tidy package — the dice pool. It’s just as exciting to me as a player or game master, as it stirs the imagination, reduces repetition, and keeps me vested in everyone’s actions, not only my own. It helps reinforce that side effects can help move the story along and create more memorable sessions by adding details and prompting creative contributions that players might otherwise overlook.

So yeah, that’s all pretty nerdy. But these are the sorts of things I think about every day. While this concept of Terminal Outcomes isn’t the be-all, end-all for game design, it’s one of the many tools available to consider. Personally, this approach opened my eyes and helped me look past some design obstacles to see that there are always more ways to approach a problem. Or to resolve a skill check.

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