What are rules, anyway?

Buckle up, this is a long one.

It is an incredible but nevertheless true fact that you can homebrew any TRPG until it becomes any other TRPG. This is done with a finite sequence of substitutions, additions, and subtraction of rules. Kind of like every word can become any other word by mean of addition, subtraction, or substitution of the letters from which it is formed. (See Levenshtein distance for more.)

A wise hobbyist, or perhaps a fool, would then try to subtract every conceivable rule to obtain the minimum viable TRPG. Indeed, since this hobby is full of people who love information theory, the research of this "elegance" appears almost obligatory once the, ahem, rules of this game are laid out.

I propose that if you remove every rule from a TRPG what is left is an empty container, itself of very notable nature. One may be unaware consciously of the existence of this container, but it is absolutely necessary to play any game. It is a frame of mind, a conceptual boundary, a lens, and its name is "playfulness", or "being in the mood to play".

Indeed, a game is created when someone who is in the mood to play sets arbitrary limitations on themselves and tries to achieve something. Throwing a rock is not a game, but trying to make it skip on water can be.

(Of course I don't claim this to be The definition of game, for anyone can easily conjure up counter-examples, such as professional football, where having fun is not necessarily on the agenda.)

What I find incredible, and amusing, is how different TRPGs can have nuance regarding what are rules. Fabula Ultima is a tight-packed engine that kindly requests you try it out as-is before you try to homebrew it, because it is made by a good game designer who understands the cogs that contribute to its functioning (and even she is surprised by some of the system's emergent properties!) The game designer is asking the players to play withing these boundaries, to color within the lines, before they inevitably start to desire more.

D&D on the other hand, is a hodge-podge of rules adapted from previous things. It's DNA has traces of Chainmail, Outdoor Survival, the Braunsteins of David Wesely and the Blackmoor of David Arneson, some other ship game whose name escapes me, and many more. The magic system is inspired by the novels of Jack Vance, and the alignment system from Michael Moorcock. There's the whole Appendix N. We could probably keep talking about this for a while, and indeed many people have dedicated a substantial amount of hours to do just that. It's a byproduct of grafting together subsystems and hoping it all works out. (By the way: this brokenness is important because it drives many people to create their own game.)

Earlier, I said that rules are limitations, specifically self-imposed limitations to make obtaining a goal more challenging. But there's two ways to see them: limitations, yes, but also tools. If on one hand the rules that regulate attacks in D&D force you to resolve attacks with them, on the other you have the almost certainty (rule 0 notwithstanding) that if you attack, it's going to get resolved like that. Which means you can tweak the variables this procedure uses, to maximize your opportunities of success.

So there you have it, rules are limitations, but also tools. It depends on the point of view.