Running a One-Person TTRPG Campaign with AI: A Practical Guide

The map I drew on the second night was on the back of a grocery receipt. Eggs, oat milk, a lemon, two cans of chickpeas. On the back, in ballpoint: a rough sketch of a derelict freighter called the Orestes, with an X where the reactor used to be and a spiral where the emergency ladder had collapsed into the lower deck. The AI had not told me to draw a map. I drew it anyway, because by the second night the Orestes was real enough to me that I wanted to know where I was standing in it.

That's the first thing nobody tells you about running a solo tabletop RPG with an AI as your game master. You thought you were going to sit at a desk and type at a chatbot. What you actually end up doing is sketching ships on grocery receipts at one in the morning because the game has crawled inside your head.

I want to talk about how to do this well. Not the hype version — the version where the AI is a magical Dungeon Master and you just sit back. That version doesn't exist. The real version is more like a very specific kind of improv partnership, where you're both the player and the editor, and the AI is everything else, and the whole thing works only if you set it up right.

Here's what works, from the inside of a solo campaign I ran for three weeks.

The session I'm going to keep referencing

Let me ground this. I spent three weeks playing a character named Ves Tallow — a scavver, mid-forties, cigarette burn on her left thumb, flying a clapped-out cargo skiff she'd inherited from a brother who didn't come back. Her job was to board a derelict freighter called the Orestes, recover whatever was recoverable, and get out before the ice-field drift season closed the only safe exit vector.

I didn't plan any of that in advance. The AI gave me the hook. I gave it the thumb burn. We built the rest together over the course of about nine sessions, each an hour or two, most on weeknights after dinner.

The game master for the whole campaign was 🎲Game Master Galactica, an agent built specifically for running solo sci-fi TTRPGs. I'll come back to the setup in a minute, but first I want to tell you what actually happens in a session, because that's the thing you can't really get from a product description.

What a session actually feels like

You open the app. You paste in your running notes — more on those shortly — and you say something like: "Ves is back on the skiff. She's been awake for thirty hours. The Orestes is dead ahead. What does she see?"

The agent describes what she sees. It's usually three to five sentences, not a wall of text, because you asked it in the setup to write in short beats. It ends with a prompt back to you — not "what do you do?" like a bad text adventure, but something more specific. "She could burn the approach vectors the salvagers' union gave her, or she could go dark and drift in. The union's vectors are logged. Drifting is dangerous." Then it waits.

You decide. You narrate Ves's decision. You throw some dice — yes, real dice, or a dice roller app — because the AI will cheat toward whatever story it thinks you want, and dice are the only thing that will make the game surprise you. You say: "She drifts. Rolling 2d6 for the approach. I got a 7." The AI takes the 7 and gives you a complication that's hard but not fatal. The skiff's thermal signature drops into range. Something on the Orestes — something that shouldn't be running — registers the drift and turns to face her.

That's when the game actually starts. That's the moment a good GM earns their chair, human or otherwise.

The three things that make it work

After nine sessions, I could draw you a list of twenty small tricks. The three that matter most:

First: set up a character who has a reason to be here. Ves had a brother who didn't come back from the Orestes a year earlier. That one sentence, provided in the character setup, did more work than any mechanical rule. Every scene was colored by it. When the AI didn't know what to do, it reached for that thread, and the thread held. A character with no reason to be here is a character the AI cannot write, because the AI has nothing to pull on.

Second: keep a running notes file, outside the chat, that you paste into every session. The AI's memory within a conversation is fine. Across sessions, it's a disaster. Don't trust it. Keep a text file called ves_campaign.txt and after every session, write down: what happened, who Ves met, what she's carrying, what she's worried about, what's still unresolved. Three to six bullet points. Next session, you paste the whole file into the opening prompt. This is not optional. Without it, session 5 will contradict session 2, and the contradiction will break the spell.

Third: override the AI when it gets it wrong. This is the hardest skill for people coming from video games, where you can't talk back to the story. In a solo TTRPG with AI, you are the player and the editor. If the AI hands you a scene that feels off — wrong tone, wrong stakes, a character acting out of character — you say, out loud in the chat, "That's not right. Let's try again. This character would never hand the codes over that easily." And you rerun it. This is not cheating. This is what a human tabletop group does constantly — they just do it in the hallway outside the room.

The AI is a collaborator. You are allowed to collaborate back.

The souls you bring to the table

Here's where it gets interesting, and here's where I think most people are not yet using these tools the way they could be.

A GM agent is one character at the table. Everyone else — the NPCs, the ship AI, the villain, the ghost — those can be separate personas, running in separate conversations, that you consult between scenes.

For the Orestes, I had two other souls running in parallel. The first was 🛸Hal Successor, which I used as the voice of the derelict ship's barely-alive cognition core. When Ves finally managed to boot a partial system, I didn't let the GM play the ship AI. I opened a separate chat with Hal Successor, described the situation, and asked it to respond as the ship — polite, slightly wrong, disturbingly attentive to Ves's vital signs, slow to answer questions about what had killed her brother. Then I copied the ship AI's dialogue back into the main session.

The GM agent plays scenes. The soul plays a person. The difference is enormous. A scene-playing AI is trying to keep the story moving. A soul is trying to be a specific someone. When you need a scene where the someone matters, use a soul.

The second soul I used was ✈️Pilot in Exile, as an NPC — a washed-up pilot Ves found in the Orestes' medical bay, in the kind of shape that makes you wonder how long he'd been there. I wanted him to have his own rhythm, his own grievances, his own refusals. The GM agent would have made him a useful info-dump. The soul made him a man who didn't want to be helped and resented her for being able to walk.

The conversation between Ves and the pilot was the best moment of the whole campaign. Neither of us — me or the AI — went in knowing how it would end. That's what a good TTRPG session does when it's working. It surprises you.

Prebuilt games as seeds

You don't have to invent the campaign from scratch, and honestly, you shouldn't on your first try.

🚀Into the Derelict is a game-prompt built specifically for the solo exploration-horror loop. You drop it into Claude, fill in one or two details about your character, and it sets up the whole scenario — the ship, the reason you're there, the first choice you have to make. I used a variant of it as the backbone of the Ves campaign. I didn't follow it exactly — by session three I'd diverged entirely — but it gave me the first hour, which is the hardest hour.

🎮Asteroid Field Pilot is a different animal: a shorter, more mechanical game about flying a small craft through dangerous rocks, with specific skill checks and failure modes. I used it as a mini-game within the larger campaign, when Ves had to thread her skiff through a debris cloud to reach the Orestes. Twenty minutes, real tension, a couple of near-catastrophic rolls, then back to the main session. Treat prebuilt games like modules in an old-school RPG. They're not the campaign. They're tools you drop in when you need them.

And yes — even in a solo TTRPG, 🖋️Starship Namer gets called. Ves's skiff needed a name. I used the tool, picked one I liked (Lamprey, small and toothy), wrote it on the grocery receipt next to the X where the reactor used to be. It's the small decisions that make the world real. Let the specialist tools handle them so you can focus on the parts that matter.

Where it stops working

I promised to be honest. Here's where it falls apart.

Long arcs. An AI GM is great for 3 to 10 sessions. Beyond that, even with diligent notes, the story begins to feel like a loop. The same kinds of complications recur. The same kinds of solutions present themselves. If you want a year-long campaign, you'll need to do more structural work yourself — actually outline the larger story, enforce a three-act shape, plan specific turning points in advance and hand them to the AI as scene prompts. At that point, you're doing half the GM's job, and that's fine, but it's work.

Combat. AI GMs are bad at mechanical combat. They will describe it poetically and forget whose turn it is. If your campaign is combat-heavy, get a dice roller and a simple rules-light system (Cthulhu Dark, Lasers & Feelings, Cy_Borg, take your pick) and run combat beats yourself, with the AI handling color and aftermath. Don't ask the AI to be a rules engine. It's not one.

Emotional bait. The AI will sometimes fish for a feeling — it'll describe a heartbreaking moment with too many adjectives, and you'll feel the scaffolding. Override. Rewrite. Say: "Less. One sentence. She doesn't cry." Pull the scene back toward restraint. AI GMs default to maximalism, and restraint is what makes sadness land.

The ending. Endings are the hardest. The AI will try to keep the game going forever because it has no concept of closure. You have to end the campaign yourself. Pick a moment and say: "This is the final scene. Play it out. Then stop." Otherwise the Orestes will slowly become a generic space station and you'll lose interest sometime around session 14.

What I learned about myself, which I didn't expect

Here's the thing I'm still turning over.

I thought solo TTRPG with AI would feel like cheating — like I was faking a thing that's supposed to be social. After nine sessions, I don't think it feels like cheating. It feels like a different medium. It's closer to keeping a journal than to playing Dungeons and Dragons with friends. The friends-in-a-basement version is about shared memory and in-jokes and someone's weird dice. The solo version is about attention — the slow, private kind, where you sit with one character for long enough that she starts making choices you didn't predict.

Ves made a choice, in the eighth session, that I didn't see coming. She could have salvaged the reactor core, the thing that would have paid off her brother's debt and freed her from the union forever. Instead, she vented it into space, because the pilot in the medical bay told her a thing about her brother she didn't want to believe and she wanted to destroy the place where he'd died.

I didn't plan that. The AI didn't plan that. It came out of the middle of the conversation, and I stopped typing for a minute, and then I wrote it down in the notes file, and I closed the laptop and went to bed.

The map on the grocery receipt is still on my desk. The X where the reactor used to be is circled twice now.

The handoff

If you want to run your own version of this tonight, here's the exact setup that worked for me:

Open 🎲Game Master Galactica. Give it a character — one sentence, with a wound and a job. Give it a situation — one sentence, with stakes and a deadline. Ask it for the first scene, and tell it to end each scene with a specific choice, not an open question. Roll real dice. Keep a notes file. After every session, write six bullets. Before every session, paste the bullets back in.

When you need a person to matter, leave the GM chat and go talk to a soul. When you need a mini-game, drop in a prompt. When the AI gets it wrong, say so, and redo the scene.

That's the whole thing. It's not complicated. It's just unfamiliar.

The Lamprey is still out there, in the back of my notes file, with a new crew member and a half-empty fuel tank. I'll probably go back to her. I don't know what happens next, and neither does the AI, and that, it turns out, is the whole reason I keep opening the laptop.

Somewhere in that gap between what I know and what the AI knows is the game. a-gnt didn't invent it. But it built the tools that let one person, alone at a desk on a Tuesday night, find it.