RULEBOOK AS NORTH STAR

there are a lot of ways you can conceptualize TTRPGS. usually i use the lens of 'collaborative storytelling' but for this post i am going to say that playing TTRPGs is just playing pretend. now if you imagine a big dragon, and a guy hitting him with a sword, that's all well and good. you can picture it in your head however you want to. maybe the dragon is green, or red, or a dull grey. maybe it's a slithering wyrm or a classic fantasy four-legged affair.  maybe the guy is grizzled and missing an eye or maybe he's wearing gleaming armour carried for him by his retinue of personal slaves. but as long as the guy and the dragon are just in your head, they exist in only one form, one perfect form, transmitted from you and to you. 

the moment someone else gets to make stuff up with you, that goes out of the window. now there's ambiguity. when you say 'a guy is hitting a big dragon with a sword', every single person who hears it will likely imagine a differnet guy, a different sword, a different dragon, a different scale for 'big'. you can add detail to the fantasy to remedy this, of course. you can say 'a frail, wasted hero is feebly striking at a bulbous pink-scaled wyrm with a rusted falchion'. now everyone's on the same page. but part of playing pretend is cause and effect, moving beyond single perfect images and to the next thing that happens. sometimes--often--the person who is the loudest or most convincing or makes the most sense will make a suggestion for what happens next and everyone will agree. but as you go through scenes and images, the tiny differences that are inevitable no matter how lovingly you describe every detail of the fantasy will build and compound. 

and so you end up with irreconcilable differences, ruptures in the fantasy that require serious suturing to resolve. sometimes you can't resolve them at all. and this is where a TTRPG rulebook comes in, whether it's a 200-word collection of simple abstractions or a biblical tome of detailed rules for how wind resistance and the turn of the earth impact bullet trajectories. i often talk about the rulebook as a co-writer, but in this frame of understanding it's more of a guiding light. you look the rulebook and understand the bounds and limits and space of your fantasy. you still have your sandbox, but you're all using the same shovel now. the simplest possible TTRPG, in this interpretation, is kids on the playground playing 'house' or 'cops and robbers'. 

i'm not sure if this is the most useful way for me to think of TTRPG rulebooks. i still prefer my co-author model, the metaphor of alchemy turning story into games into more story, or a slightly more dorky model centering on legibility and knowledge production that i might get into here at some point too. but it's a useful one for practical purposes, for deciding what you need to put in a rulebook and what isn't--where will the fantasies diverge if you don't bring them together?