Reflections on RPG Rules
In this post I discuss RPG rule design, and in particular three purposes those rules serve within the game. I assume the reader is familiar with the basic components of RPGs like the GM, the Players, PCs vs NPCs, and dice. Those not familiar with them should probably read post 3 first.
Rules define what is and isn’t possible, thus helping define the world and the capabilities of the beings in it. In many ways, the rules serve as the definition of the world in which the collective fantasy is taking place.
RPGs are collaborative story telling and it’s important for all collaborators to have the same understanding of the world. If I say someone is a promising but junior wizard
what does that mean? Can they use magic to prepare dinner? Can they read minds? Can a more senior wizard block their magic? Does their magic have side-effects? Answers to these questions, when posed in a way that applies to more than just one character, are rules.
Some rules are fairly fuzzy, appealing to the players’ understanding of the world we live in to resolve most matters. They might say something like the PCs are unremarkable soldiers during World War II
and assume payers can figure it out from there. They also might introduce fantastical elements by analogy, such as magic in the game world serves a similar role as computing does in the real world, with similar breadth of use and limitations
or a character with the
bouncy” superpower can jump 10 times as far as an ordinary human.”
Other rules are much more precise, laying out specific numbers and distributions. For example, in Dungeons and Dragons 5th edition we find the following rule:
When you make a high jump, you leap into the air a number of feet equal to 3 + your Strength modifier if you move at least 10 feet on foot immediately before the jump. […] You can extend your arms half your height above yourself during the jump. Thus, you can reach above you a distance equal to the height of the jump plus 1½ times your height.
Coupled with distributions of the Strength modifier
it refers to, this gives not only heights people can jump but also what percentage of people can jump to what height. It also tells us that an short (5 foot tall) average-strength (+0 modifier) adult human can dunk a basketball with ease (reaching 10 feet 6 inches compared to an NBA basket height of 10 feet).
Precise rules tend to incentivize calculated strategies based on how the world is defined to work. Fuzzy rules tend to incentivize common-sense strategies based on the players’ experience and intuition.
The feel of an RPG will tend to be swayed by where the focus of the rules lies. If there are rules for making progress in political discourse but none for making progress in military conquest it is a safe bet that Players and GMs both with chose actions that lie more in the direction of politics than combat.
Play is also likely to favor politics over conquest there are rules for both but more (or more detailed) rules about politics. Relative detail has a larger impact on how a game feels than total detail.
For example, Dungeons and Dragons devotes entire chapters of their rule books to combat and magic, so it is unsurprising that their games tend to have a lot of fighting and their stories tend to be dominated by magic. Their jumping rule quoted above is just a few sentences in a several-hundred-page book of rules, so it is very unlikely that a player will decide to use their rules-granted ability to leap over small buildings as a defining characteristic of their play. In hundreds of hours of play I can’t recall a single time when jumping heights were more than a tiny footnote to the story being told.
By contrast, Lasers and Feelings fits all their rules into just a few paragraphs. Half of those rules (and half of the game’s name) relate to social interactions, with a corresponding impact the focus of play. If we added an entire paragraph on jumping to that system then it would likely have a huge impact on the gameplay, almost as if we had said this is a game about space combat, social interactions, and jumping over tall obstacles.
The characters in an RPG should each have their own personality, motivation, and history, creating variety in what they will do. But in many RPGs the rules also help support them varying in what the can do. One might be might be strong, another fast; one might be a dead shot with a pistol, another able to read people’s minds; one might suffer withdrawal if they stop feeding their addiction, another might be unable to stop themselves once they start talking.
All of these kinds of differences can be handled without rules. A player can simply write good at singing but trips a lot
in their notes about their PC and then bring those out during play. However, in my experience many players differ in how superhuman they think their own and all other PCs should be, resulting in increasing tension between players the longer such unruled divergences in ability are allowed to unfold. Having rules about character ability can help balance power levels and facilitate cooperative play.
Rules that describe options in character creation must also describe the world with enough detail to support the variety they introduce. In order to use rules to say that some character is very good at jumping I need to define what a normal jump is so I can define how far beyond that the specific character is. Hence, all of the comments in the previous section about defining the world, including the impacts of specificity and focus, also apply when defining characters.
Character ability rules are also the primary driver of what I’ve previously written about as The Other Game
of RPGs (see post 8) where some players enjoy trying to optimize their characters’ ability to do something within the constraints of a large set of interacting rules.
In addition to static abilities, most RPGs have some way of tracking aspects of a character that change significantly over the course of a single play session, or even a single scene within the story. Two classes of time-varying attributes deserve particular attention.
Many RPGs have some form of a track to defeat (or success). Perhaps there’s a system of wounds or stressors and rules for when they are gained and how they are lost and what impact they have on the PC’s odds of success. Perhaps there’s a pool of points or chits or bandages or favors that intermediate defeats consume, and when none are left the next small loss becomes a big loss.
Whether they’re emotionally beat down or physically beat up, it may seem odd to focus on defeat like this. But in many game genres the alternatives are either low-stakes games where failure doesn’t happen or anticlimactic games where one failure ends it all. The risk of failure is a useful part of storytelling primarily if it spans a significant part of the story or scene, with slow build-up and large stakes.
Some systems have a slippery-slope mechanic where intermediate failures make future failures more likely, which can result in a feeling of doom and horror as defeat races up to meet the players in an unstoppable acceleration. For example, Savage Worlds’ wounds make combat feel gritty and worth avoiding; Betrayal at the House on the Hill’s nonlinear dice pool losses with choices on where damage goes create a building horror aesthetic.
Some systems have a self-correcting mechanic where intermediate failures make future failures less likely, which can result in an optimistic learning-from-your-mistakes experience. I’ve only seen this on a larger time scale than a single scene; for example Dungeon World marks experience on a failure, reducing its sting while also leveling the power of the group of PCs and encouraging players to pick challenging missions.
Some systems try to heighten the perceived stakes by using some kind of complicated multi-state system where the number you usually look at goes down quickly but some less-visible number bumps it up again, giving a frequent sense of near-failure turning into relief. For example, Dungeons and Dragons has a clearly-visible and frequently-interacted-with pool of hit points
that seem to indicate how much beating a character can take, but also multiple other pools that can be used to replenish hit points within a scene, meaning they can actually take much more than it looks like they can which helps create the hero aesthetic the game is known for.
Some systems transparently pair failures in one type of action with incentives to either continue it or try something else. One of the most successful of these is used in several rules-lite single-session RPGs, but I think it first appeared in All Out of Bubblegum. In these models, all uncertain PC actions are categorized as high-stres actions where energy and rage might help or low-stress actions where calm and patience might help. The progress-to-defeat tracker marks how stressed the character is, so as their stress increases they get better at one kind of action but worse at another.
Characters in many RPGs have some resources that might run out. This could be something tangible from the real world, like money or ammunition; or it could be something intangible like patience, social capital, or magical energy.
Managing these resources can have a major impact on the feel of a game. You pay attention to what you need but might run out of. If I have to track how many arrows I have and how much space I have to carry more arrows in, I might make decisions based on the availability of fletchers or pick a non-archery PC to avoid thinking about it entirely. Conversely, if I don’t have to track arrows at all then I might use bundles of them to start a campfire or other nonsensical actions.
One interesting resource management system I first encountered in Gamma World 7e had a distinction between conserving
and going whole hog.
If you shoot your rifle once in a fight you still have ammo afterward; if you shoot it twice or more it lasts for the whole fight, but afterward it’s out of ammo. Here the rule very clearly chose a decision for PCs to make, an more clear intentional focusing effort than most I see in RPGs.
Several games use some kind of logarithmic or bucketed system, particularly for money. For example, you might have a 6-digit bank account; you can spend 4-digit costs freely, 5-digit costs once per play session, and if you ever do a 6-digit purchase you’re left with a 5-digit bank account thereafter. Or maybe you’re at wealth level 4 and can buy anything listed at that level or below. I’ve talked to some GMs who have tried using a similar model for other resources like magical energy or distance from failure, but none have reported very high satisfaction with that approach.
In the real world, when I attempt something I don’t know it if will work in advance. In an RPG that can be simulated by letting the GM decide what works and what doesn’t, but GM arbitrage can create a tension where players perceive the GM as picking favorites or vetoing their good ideas. Thus, it is usually preferable to have the possibility of failure be handled by rules instead of by people.
There are many, many ways that RPG rules handle uncertainty. They vary both in the specific chaos they introduce (see post 5) and in where the chaos is applied.
Much of the complexity of larger rule systems is in nuance of when and how much uncertainty is added. Many such systems have a hierarchy of rules, one superseding another; for example, perhaps there’s a no-uncertainty rule magical levitation can be maintained for 10 minutes,
plus a generic uncertainty rule if you get hurt when maintaining a magical effect, here’s the odds of it ending early,
plus a more specific rule you’re half as likely to have flight-based magic end early as other magic
modifying the odds of the generic rule, and so on.
Several rules-lite RPG systems have some version of the following single unifying rule: When a player proposes an action, the GM decides if it will work, can’t work, or is uncertain. If it is uncertain, it is resolved as follows: [chaos rule]
.
A small step up from this is to allow the GM to pick a sliding scale of chaos odds (e.g. that sounds hard, so let’s use the
hard” odds for it”), or to allow the PCs one or two situations where the odds are different for them then they would be for other characters (I’ve got the ring of invisibility so my odds for this are much higher than normal
).
More complicated ways of handling uncertainty and odds can have a significant impact on the aesthetics of the game, a subject that I’ve written more about in post 620.
RPGs vary in how rigid the uncertainty mechanism is, both in how they are officially defined and in how they are played.
Some RPGs handle uncertainty with odds that are selected by the GM and kept secret from the Players. Players state what they attempt, GM asks them to roll dice or draw a card or the like, and then the GM tells them how successful they were. This design gives the GM the ability to fudge the numbers to fit the story, making similar situations hard in one context and easy in another to facilitate specific outcomes. It also makes it hard for the players to know how likely a particular course of action is, which can either create a feeling of mystery or frustration depending on the player and their level of trust in their GM.
Some RPGs let the GM pick the odds, but have them state those odds before the dice are thrown or cards pulled. Rules-lite versions of this might give the GM carte blanche in picking odds, while rules-heavier versions will give guidelines and examples to guide the odds selection.
Some RPGs have objective rules for what the odds are. These can vary from a simple all uncertain events have a 50% chance of success
to a complicated system of look-up tables and situational modifiers. Rules-heavy RPGs with precomputable odds tend to encourage play styles where the players plan out actions in some detail to maximize their odds, drawing focus to the rules themselves. Conversely, the rules-lite versions can make strategy feel like mere garnish because the specifics of the players’ plans have limited impact on their odds of success. Even in the most rigid system, the GMs is able to steer the outcome of events by picking what situations the players face, and thus which and how many uncertain situations they encounter.
In my experience, the rigidity of the rules system influences the play experience significantly, tipping the balance between playing roles and playing games. However, I have not seen rigidity have much impact on world in which it takes place.