From Fate to Stage Whisper: Building a Solo TTRPG System for AI GM

You probably started with D&D. Most people do.

Dungeons & Dragons is the big one, the cultural anchor, the ttrpg that everyone knows. it's what's popularised tabletop gaming as an activity, and it's what people think about when they hear "tabletop RPG." but here's the thing: D&D was designed for a human DM juggling monsters, story beats, and player shenanigans in real time. an AI DM doesn't work that way.

D&D is a fantastic and complex system. it has an extensive world and lore, published campaigns, tactically rich combat, and a character progression system that players can spend hours theorycrafting. the problem is that all this complexity works against you when you're trying to run it with an AI.

A lot of D&D gameplay relies on the precise execution of combat rules, and a fine balance between mechanically following the letter of those rules and a little creative interpretation to allow players freedom to be creative while still forcing them to pick their moves carefully. with the right harness and code to assist, an AI could be made to run D&D combat and campaigns, but doing so would require a lot of upfront work writing code to enforce the mechanics and ensure the AI correctly applies the rules.

So what happens when you try to play D&D with an AI? it might be able to run your first campaign fine, but once it gets to the intricacies of combat, it's going to struggle to keep track of all your stats, HP, status effects across every character and enemy. and when a large part of the enjoyment of D&D is in how well you've crafted your character and how well you can use your skills, this really affects the experience.

There's a Whole World of TTRPGs Out There

Here's something I didn't realise until relatively recently: there's a huge number of tabletop RPG systems out there. hundreds, maybe thousands. different rules, different settings. some are as intricate or even more intricate than D&D.

One you might have heard of is Shadowrun, which has its own series of video games. like D&D, Shadowrun has a lot of focus on stats and player progression, and is tied to a specific world with pre-existing lore.

But there are also simpler systems, that have less emphasis on stats and less rigid tie-in to a specific setting. one such system is Fate.

Why Fate Works Better for AI GM

Fate is a much simpler system than D&D, and is deliberately agnostic to setting and genre. it doesn't tie you into a fantasy world or a cyberpunk world. it just says: whatever world you choose to play in, here are the framework for the GM to build out the narrative and the mechanics to challenge the players with.

Fate focuses much more on the narrative experience and collaborative storytelling aspects of tabletop RPG, and encourages the players to build part of the narrative alongside the GM. rather than relying on detailed stats to deliver the challenge, there is a relatively simple skill check system that serves as a way to encourage players to try to solve problems creatively, and to add some randomness and surprises when the dice roll doesn't go the way either the player or GM expects.

This turns out to be much better for playing with an AI as the GM. the focus on collaborative storytelling allows the player to help shape the world rather than have the GM solely create it. mechanics are relatively simple and easy for an AI to execute without glaring errors. and the way that dice rolls serve to add unexpected complications rather than to punish the player helps drive the narrative in ways that are much more dynamic than an AI just writing the whole plot.

But Fate Isn't Perfect for Solo AI GM

The first problem with Fate for solo AI play is the character creation process. Fate is really designed to be played with more than one player in addition to the GM. the character creation process helps create a shared narrative between multiple players, giving them clear shared history before the first session. but this is a relatively slow process, and only works when there are multiple players. it makes less sense to do this when there's only one player.

The second issue is that although the mechanics of skill checks are much simpler, the unusual dice system and unfamiliar terminology: high concept, aspects, fudge/fate points, stunts, are somewhat difficult for those unfamiliar with Fate or TTRPGs to understand. enough that it can cause apprehension for someone wanting to pick up gameplay casually.

Building Stage Whisper TTRPG

So I decided to come up with my own ttrpg system focused on being played solo with an AI GM. it has the same focus on collaborative storytelling as Fate, but with modifications:

Character creation is greatly streamlined. the goal is to get players into gameplay as soon as possible. in solo play, a lot of the details can be filled in as the game goes, so it's no longer needed at the start.

The dice system is simplified to a straightforward numerical system using 6-sided dice, that's more approachable to new players.

Players still get a skill pyramid, but the skills are simplified, combining things like athletics and physique, and adding provisions for knowledge and magic skills for the genres that benefit from them.

High concepts, aspects, and stunts are removed and replaced with a single "special move" which grants a bonus to a roll. it's simpler but much easier to explain to newcomers.

Fate points and compels are removed and re-introduced as Style points, to be given out when players roleplay their character well, even if it hurts them. this is a substitute for compels, making the act of the compel purely voluntary but rewarded by points. this makes Style points more similar to Inspiration points from D&D which are awarded similarly for particularly creative play. the naming also reflects this: you receive Style points by playing with style, and you spend Style points to give a +2 to your roll so that you can execute your move with style.

NPCs are given skills too. this allows solo players to build a party of NPCs that can solve challenges together.

The role of the GM in developing the skills and relationships of the NPC is enshrined in the rules, and the SRD is delivered in markdown format for easy digesting by an LLM.

Between these changes, what I call the Stage Whisper TTRPG system is simpler to play and execute for a solo session with an AI as GM.

The Stage Whisper SRD

The full rules are short enough to include here. the Stage Whisper TTRPG system is open source (CC-BY) and available for anyone to use, modify, or build upon.

Download the Stage Whisper SRD

If you're interested in running tabletop RPGs with an AI GM, or just want a simpler system for solo play, give it a read. and if you end up using it for anything, I'd love to hear about it.