Staring Back at the Invisible

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We've come to the final entry in the Lexicon series. If you're new, hi!

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Back in our very first entry, we met the goofy metaphor of the “Invisible Rulebooks,” the rules which can't be found in the "rules" part of the Book of Rules ... but they're still rules, because in an RPG, any fact with tactical relevance is the equal of a rule, whether it's a "+1 to hit" kind of fact or "the Duke is self-conscious about his baldness" kind of fact or "this is a genre where protagonists can’t die just by slipping on a banana peel" kind of fact, or many others.

It’s a metaphor; Invisible Rules aren't always literally invisible. If an adventure module specifies that the Duke is self-conscious, it's right there on the page, plainly visible but still (in this context) an "Invisible Rule," because we won’t see it in the “Rules.”

Rules (of every kind) have some other qualities worth noticing, beyond Visible/Invisible. Let’s dive into our final set of terms, laying those crucial qualities bare.


Let's say we're imagining a merchant, in a fantasy world. My idea of what "fantasy merchant" means might come from a book of real history, or a videogame, or from personal memories of a hilarious NPC my favorite GM in the 80s portrayed with an AWFUL Cockney accent. Most likely it's all of those, and more. I think about fantasy merchants a lot.

If you and I have played the same videogame, we have some common ground. This makes that portion of our Invisible Rulebooks shareable between you and I.

If you and I haven’t read the same history book, I could loan mine to you, if you want, and if you're interested in the topic or if it seems really important to our campaign, maybe you'll read it. So that's another degree of (potentially) "shareable."

But there's no way for you to go back in time, in MY life, and experience the exquisite agony of that hilarious NPC with the terrible accent. The best I can do is describe it, which is another kind of "shareable" that's much more limited. If your own gaming life includes a similar NPC, that’s a kind of shareable too, though we might also be making assumptions about the similarity of our experiences that are only partially true.

If we're gaming in a gameworld we both enjoy, we've both probably delved into some of the published world material for it ... and, in certain playstyles (like mine) that's such a critical form of shareability that the facts presented in the worldbooks almost REPLACE the "core rules" as OUR core rules. Those rules are “invisible,” but they’re right there on the page, and they matter a lot to us if we care about this setting being our setting for this campaign.

Some of my impressions of merchants are also based on modern shop employees, or characters from movies, things like that. I'm only semi-conscious of that vast stew of influences, which makes them difficult to share. You probably have a comparable, but different, set of impressions. Those impressions can still inform how you roleplay, and how I GM, so they're still part of our Invisible Rulebooks, but they're poor on this quality of shareability.

And of course, one of the advantages of the Visible Rulebooks is they're super-shareable, and labeled explicitly as rules. One of many reasons why, in MOST playstyles, the core rules ARE the core rules.

Anyway, "shareable" is a useful concept, and it (in the main) means what it sounds like. Moving on.


Wait, didn't we DO this one? Sure did, but we started with a focus on resources the PCs can use to solve problems, back in this article.

But any fact with tactical relevance is a rule, and resources are just sets of facts. The existence of the Duke's toupee (a gameworld fact) is a rule. The law of universal gravitation that can make it flutter into a canyon, is a rule (most gameworlds have it, though it works differently in James Bond's world than ours, ditto for Wile E. Coyote). The formal game-system rules for falling damage if he dives after it and plunges 200 feet to the rocks below, are rules. They all live somewhere on the spectrum from the Ephemeral to the Reliable. The Duke’s toupee might be highly ephemeral if it only matters during one adventure, but the law of universal gravitation tends to stick around.

Worth noting: a fact the designer imagined as Ephemeral, or that the Game Master intended as Ephemeral, is something the PCs might still find creative ways to leverage, many sessions, even many real-world years, down the line in a long campaign, and that's awesome, and something we want to keep with us as we design. When the PCs concoct an elaborate plan depending on the existence of a toupee they remember from five years ago? Oh my god, yes please.

So, Ephemeral and Reliable aren't new to the Lexicon, but it's time to recognize that they're part of our set of descriptors for rules, because any fact can be a rule, which means we can design using any body of facts.


This one's pretty simple. Some rules have no flex. They are FIRM rules, rock-hard in some cases. If firing a crossbow takes a -10 penalty in total darkness, that -10 penalty is very clear, objectively-defined, and not something to be nuanced or haggled over. It just IS. It is firm. Visible Rules lean ... firmly (though not invariably) into firmness.

Many Invisible Rules are just as firm, though. Newton's universal gravitation is, in _most_ game worlds, extra-crazy-firm. The Duke is definitely bald. Firm rule. Diamond firm, Adamantium firm. Southern Moss-Type Elves can see in the dark? Firmly so. Only an equally-firm declaration of exception ("Rufus the Elf is blind") can change that, case-by-case.

But the Duke's self-consciousness about his baldness, while it may definitely absolutely exist, has a lot of room for nuance when we treat it as a rule. It absolutely IS a rule – it's a fact the PCs can make tactically relevant – but, there's flex because self-consciousness is a softer concept, with a lot of variables, a lot of range. It has gradients. It has tipping points. It has overlaps. There's a lot of latitude for the GM to interpret it very differently from another GM, with both interpretations being equally fair. That same lack of firmness – softness – can make it attractive to PCs looking to use it creatively, and for that to work, we (the players) must be confident that our GM will give us a fair shake when we do.

Firm's a simple term with big implications. Some of the Invisible Rules are firm, but a lot of them are soft, and we like that. It's good for the kind of gameplay I build for, and the kind of gamer I am.


I need "diegetic" a lot. I don't enjoy the word itself, but I try to use standard game-design terms when I can, and it's a standard. A fact is diegetic if it exists within the gameworld. The Duke's toupee is diegetic; the Duke's self-consciousness is diegetic. The rules for falling damage are NOT diegetic. They're extradiegetic rules that enjoy clear correspondence to a reality within the gameworld, but the Duke doesn't know about the Visible Rules. He doesn't even know he's fictional. He's troubled enough by his baldness, so please don't tell him.

The idea of "clear correspondence" between diegetic and extradiegetic elements can be important if you lean a lot into the Visible Rules. I don't often, but when I do, correspondence is a useful concept. Very briefly: if “one point of ammo” for a bow [a game mechanic, and thus extradiegetic] exactly and reliably equals one arrow in the gameworld [the arrow is diegetic], that’s a case of clear correspondence. If “one point of ammo” equals a variable number of arrows because we’re modeling a week-long series of battles abstractly with just a few die-rolls, that’s a looser, less-clear level of correspondence. Game systems play at many levels of correspondence clarity (and tightness, and causality) for a lot of good reasons.


This is super-crazy-important. Something is character-facing if the Player Characters have direct awareness of it. So, the Duke's self-consciousness probably doesn't begin play as Character-Facing ... it's something of value the PCs might or might not discover, and if they do, they can exploit it or leverage it in some way. And if they never learn it, it remains diegetic (it exists in the gameworld) but it's something the PCs can't use.

The Visible Rules are never character-facing. The PCs can understand that "falling into a canyon can kill you," and some PCs can calculate acceleration and terminal velocity and stuff ... but they can never read the corresponding game-rules for falling damage. This distinction is huge; I can’t overstate it no matter how desperately I want to. The Visible Rules can in many cases be leveraged by the players, but only character-facing facts can be leveraged by the characters.

In the style I design for, the thing this entire series has been laying groundwork for discussing, the players would rather be left out of things, thank you kindly. We prefer to game by roleplaying, at least as much as possible. We game through our characters, so to solve the problems presented by the adventure, we need tools we (the characters) can know, and think about, within the imaginary world. That desire creates some style-specific needs for adventure design.


Let’s go back to the comedy-action version of the Wild West, where we are rootin' and (mayhap) tootin' as well. In our Invisible Rulebooks relating to genre conventions, we have some very interesting rules when it comes to these other qualities. They are (in many games) firmly Invisible (not codified by the game system), but are they diegetic? Are they character-facing? If we are to impress the villain by shooting his hat safely off ... he's going to be LESS impressed if he's conscious of the genre convention, and MORE impressed if he's unaware of it.

But that doesn't make it a bright line ... in order to make the shot, we (the rootin'-tootin' imaginary we) must have some confidence that we can shoot the hat safely. And maybe we misinterpret it as our pure skill, or the hand of providence recognizing our righteous good-guy intentions. And more to the point, maybe exercising genre convention means stepping halfway out of character, because that kind of convention, while it isn't wholly diegetic, and isn't wholly character-facing, can be crystal clear to the players.

This isn't meant to provide some kind of conclusion about genre convention, but to illustrate how I examine each rule when designing an adventure, a world, a resource, or even a system. A lot of this stuff, as always, is mushy, and spectral, and we try to notice.


Some folks have taken the Lexicon series as design or play theory, and maybe it's useful for that to some degree, for some folks, but that's not what I've been writing it for. This series builds the ground floor to talk about the kind of game-design techniques I'm passionate about without (fingers crossed) too many distracting asides.

And I want that very much. To talk about game design. With you. With people who game and design differently from me, but who might want to (in the grand tradition of our hobby) rummage through my stuff to pluck out a few tidbits to enhance yours. That kind of rummaging, and that kind of sharing, is good stuff.

I also hope to make connections with others who game near to my own neighborhood, but the sharing is good whether you do or not.

My kind of design, when examined from a “rules” perspective, likes to emphasize tactical roleplaying with lots of potential for characterization, and while I use every tool at my disposal, it mostly lives and thrives through adventure design focused on in-character creative problem-solving. When designing problems (clusters of which form the tactical core of these adventures) I have a clear preference for the qualities of the rules I choose to design around: They tend to be Invisible, Diegetic, Ephemeral, Character-Facing, and frequently Soft (but a mix is great). Those problems need to be as non-presumptive as possible, to give the PCs (not the players) maximum latitude to create and implement solutions.


I'll be collecting the entire Lexicon series into a spiffy little PDF, knitting it all together, probably with some fresh edits and side-notes. It'll be released next to a handful of other PDFs, some of which are just fun and fluffy tools, some of which are kind of hardcore design-methody. Some will be free, some for sale. These blogposts will remain, and the PDF collecting them will be one of the free ones.

And I'll finally use the "T" word! See you there.

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This image is a Hammondal thing.
It has nothing to do with the Lexicon.
I just like it.