Librarian of Alexandria

This post was originally posted on Cohost on January 22nd, 2023. I'm cross-posting here to preserve it after the Cohost shutdown.

I hang out in a TTRPG design Discord, and something I've found there is that when people talk about rule complexity and “crunch” there's often a lot of disagreement: people define these terms differently, value them differently, and have different relative goalposts¹ for them.

Consequently, I've found myself trying to draw a fine-grained distinction between different kinds of TTRPG rule complexities. The definitions I'm about to give aren't descriptive—in fact, I think these are pretty uncontroversially not the definitions people have in mind when using these words—but adopting these as conscious jargon has really helped me clarify how I think and talk about rule complexity in TTRPGs.

In these conversations, I like to distinguish what I call rule weight, rule depth, and rule crunch as separate-but-related axes. I'll expand on this, but I also want to stress that none of these are value judgments on the games in question.

• Rule weight is about how many rules there are in the game overall. A rules-light game is a game which has few overall rules (e.g. Lasers & Feelings or Honey Heist for extreme cases) while a rules-heavy game is a game with a large number of overall rules (e.g. Burning Wheel).
• Rule depth is about how many rules interact with one another within a single situation and the amount of emergent complexity created by those rules. A rules-light game usually going to be on the shallower side²—you can't have many rules interacting if you don't have many rules!—but a rules-heavy game might be shallower or deeper. I think Blades in the Dark and Spire have a similar weight in terms of overall number of rules, but I think Blades has a much greater depth of rules: a single roll in Blades can end up involving skills, character and crew abilities, resistances, various position/effect modifiers, stress mechanics, and harm mechanics, all within a short period of time. Similarly, I'd contend that D&D 4E is a little more rules-heavy than D&D 5E but has much more rules-depth.
• Rule crunch is, more narrowly, how much math or number manipulation you need to do in order to enact the rules³. Yet again, it's hard to have a rules-light game with much crunch⁴. However, some games with heavy or deep rules still require relatively little math, while others require a lot of number juggling. I think crunch should be understood relative to how difficult the operations are for people to work with: I suspect that take-the-highest is slightly easier for most people than count-the-successes, which in turn is easier than add-up-the-modifiers especially for more numbers. Multiplication, division, and rounding all increase crunch significantly more. D&D tends to have a fair bit more crunch than other games with otherwise the same weight and depth of rules, but it's also far from the most crunchy game out there.

I said before and I want to reiterate: none of these are value judgments! When I say a game is “rules-shallow”, that doesn't mean it's a better or worse game than a “rules-deep” game. I think people can have their own preferences—my own preference, for example, is definitely for low-crunch games—but I don't think that makes them better or worse games. There are advantages to rules-light and to rules-heavy games, depending on the focus, intended play experience, level of engagement desired or demanded, and many, many other factors⁵.

A major reason I think separating these axes explicitly is valuable is because we can start to zero in on what kind of complexity people care about. Obviously, nobody is going to adopt these as “canonical definitions” overnight, but using these as a designer helps me separate out sources of complexity and In my own design work, I tend to aim for medium weight, variable amounts of depth, and low crunch. A designer with lots of disparate-but-non-interacting subsystems is aiming for heavy/shallow gameplay, while a designer with only a few basic principles that need to be kept in mind at all times might be aiming for light/deep gameplay. These are different kinds of complexity, and giving them names helps us keep track of them!