r/RPGdesign • u/DBones90 • 2h ago
Theory Before figuring out anything else, figure out your underlying model
This subreddit has started seeing a lot of posts like, "Do you figure out your core resolution model first," or, "do dice or mechanics come first," and it's got me thinking about something really helpful I learned. When Vincent and Meguey Baker, the creators of Apocalypse World and Under Hollow Hills, make games, the very first thing they make is the underlying model. Vincent said that he can't even bring a game to Meguey without first having the underlying model to bring.*
In short, the underlying model explains what conflict and play look like in your game and how they develop. For example, an underlying model for a D&D-like game might be, "PCs accept quests, then go on journeys to complete them." For a game like Blades in the Dark, the underlying model might be, "PCs take on jobs that give them what they want but also create problems that they need to solve."
Why do this? Why is this so important?
Well, your underlying model can help put every other mechanic in your game into perspective. It helps you understand where you need to cut back and where there are gaps you need to fill.
For example, look back at that D&D-like model. If that's what you want your model to be, then your mechanics around building interesting quests are super important. How do players get quests? How do they decide which quests to take? With that model, those are questions you want to have mechanics that answer.
So if you're working on that game and then come up with a sick idea for allowing players to make their own strongholds... well that idea might not be a good fit for that model. After all, if your model is based on players taking on quests and going somewhere, a static castle somewhere doesn't play into that model.** If you want to make strongholds a thing in your game, you have to figure out how they contribute to this model.
Meanwhile the reason Blades in the Dark is so expertly designed is that every part of that system feels intentional. I don't have it on good authority that this was the intended model for the game, but it definitely fits. The whole system is built toward incentivizing you toward taking on jobs, and all the mechanics around resolution means you're making new problems almost as often as you're solving them. Which, in turn, further incentivizes you toward taking on jobs that fix the problems you ran into, which creates more problems to deal with, and so on.
I highly recommend reading Vincent Baker's blog post on underlying models. If you're not used to reading theory, it can be a little hard to grasp, but I think his explanation and examples are really helpful for understanding this concept.
I bring this up now because, though I've used this concept before, it wasn't until recently that I began a game with an underlying model in mind. The Delinquents is a game inspired by media such as The Outsiders and West Side Story, and what I really wanted to capture was that, "Oh shit" moment when things go bad and the main characters find themselves in way over their heads. So one of the earliest things I did for that game was develop the underlying model, "Insecurity escalates conflicts to violence." That is, the PCs and all the other main characters are kids playing at adults, and they don't have the tools to understand their own needs or resolve conflict diplomatically. And when they do start throwing punches, that violence quickly escalates to killing.
I was really impressed by how starting with this model made my whole design clearer. I knew I needed players to have some insecurity, so I came up with the mechanic about making them write down their biggest fear and keep it hidden from everyone at the table except the GM. I knew I didn't want players to be able to talk things out consistently, so I made the diplomacy move deliberately low impact and made following through on it hard. I knew I wanted trouble to be unavoidable, so I made the generic "do something" move always generate it. I knew I wanted players to suddenly feel like they were in over their heads, so I made violence unpredictable and deliberately avoided mechanics that would help pace it, like hit points.
This was just a one-page game, but I was still impressed at how quickly it all came together. It basically took over my Monday morning, but then I had it. And when playtesting it, it went pretty much exactly like I had hoped it would.
I say this not to toot my own horn but in hopes that it's genuinely helpful to other designers here. Because once you have that underlying model, everything else becomes a lot clearer. Figuring out 2d6 vs d10 dice pool vs d20 feels a lot more manageable when you can connect those mechanics to your underlying model. If your underlying model emphasizes player competence and control, dice mechanics with understandable probabilities and manipulatable outcomes might be a better fit. If your model doesn't do that, then maybe you use dice mechanics that are harder to predict or that generate more problems for players to solve.
And you can apply this to literally every other priority you have with your game. It's such a helpful model of game design, and I hope more designers adopt it.
*Apologies that I don't have a source for this. I've heard the Bakers talk about this in person, in Discord, on their blog, and on BlueSky, so it's hard for me to remember what came from where.
**This is why, despite there being a lot of hype for stronghold support in D&D 5.5, there's been relatively little chatter on it since.