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June 25, 2026
19 min read

Playing D&D and Tabletop RPGs with Gemini: An Honest Look at What Works and What Breaks

Yes, Gemini can run a session of D&D or any other tabletop RPG. It will roleplay a Game Master, narrate a scene, read the images you hand it, and bring a warm, adventure friendly tone while it does. Upload a hand drawn battle map, paste a photo of a character sheet, drop in a screenshot of a rulebook page, and Gemini will read it back to you. Other chatbots can look at images too now, so none of this is unique to Gemini, but it handles the loop smoothly. The first hour feels strong.

Then hour three rolls around. The goblin gets a second turn because the Game Master lost track of initiative. The skeleton you dropped two rounds ago is somehow swinging again. The spell slots you spent in the narration never moved, because there is no actual character sheet. And the battle map you uploaded? Gemini just walked your party down a corridor that does not exist on it. The session that started so strong is quietly unraveling in the same way every other LLM run table does, plus a few ways that are specific to Gemini.

Below is what holds up, what breaks under the weight of a real D&D or tabletop RPG campaign, and how to actually finish one without your Game Master losing the plot. It joins our ongoing series on running tabletop games with general purpose chatbots, alongside ChatGPT, Claude, and Grok, with more likely to come.

Last updated June 26, 2026.

The Quick Verdict

  • Use Gemini as a Game Master if you are running a short one shot that stays inside a single conversation: a text only adventure of roughly an hour that never grows past the context window. For something that small and contained, it is a fun, capable improv partner.
  • Don't expect multimodal capability or a huge context window to fix the structural problems. Memory loss, rule drift, fake dice, and character drift all show up the same way they do with every other LLM run table, and image understanding adds a failure mode of its own.
  • A real tabletop RPG campaign with persistent memory, real dice, and a battle map needs a purpose built platform. That's why we built DungeonsDeep.ai.

What Actually Works

Some genuine wins, because there are some.

1. Multimodal input

Feeding pictures into the conversation is one of the nicer things about playing with Gemini. Per Google's own image understanding documentation, Gemini handles image captioning, classification, visual question answering, object detection, and segmentation. In practice, that means you can sketch a tavern on a napkin, photograph it, and have Gemini narrate the room. You can show it character art and ask it to voice the NPC. Raymond Camden's walkthrough of feeding the D&D Basic Rules PDF into Gemini proves the same thing for documents: hand it the rules, get a fully formed character back, at least at the creation stage. ChatGPT and Claude can read images too now, so Gemini is not alone here, but it handles maps, art, and rulebook pages smoothly.

2. The window is enormous

Gemini's models, from the 1.5 Pro launch with a 128K standard window and up to 1M in preview through the current 2.5 Pro line, give you more room than most. The Gemini 1.5 technical report showed near perfect recall on synthetic needle in a haystack tests across millions of tokens. For pasting in setting material, prior session recaps, character sheets, and homebrew rules, Gemini gives you the space to do it in one prompt.

3. A warm, patient improv partner

Like every modern frontier model, Gemini will say "yes, and." It leans into your weirdest character concept without judgment, and it brings a friendly, adventure ready tone that suits a night at the table. For brainstorming homebrew, sketching NPCs, or running a low stakes solo evening, it's an approachable improv partner. The free tier is generous enough that a casual player can run a few sessions without paying anything.

The trouble starts the moment you want this to be a game instead of a story.

What Breaks (And Why It's Not Your Prompt's Fault)

The failure modes below are not edge cases. They show up across every long Gemini campaign we've watched, and each one is sourced to research or writeups you can read directly.

Failure 1: Memory loss

The Gemini technical report shows strong synthetic recall on long context. Real D&D and tabletop RPG play is a different test. A UC San Diego study specifically used D&D combat to evaluate frontier LLMs on long horizon decision making and found "promising results in rule based conversation simulation" but "progressive degradation in long horizon scenarios." Recalling a fact you pasted in is not the same as tracking a world that changes every turn. Campaign play is the second thing, and the window does not help.

In DungeonsDeep.ai, your campaign is not stuffed into a single prompt. World state, character sheets, NPCs, factions, and session history live in a structured memory the platform writes to as you play, so what mattered in session two is still load bearing in session twelve. We wrote about why AI Game Masters forget your campaign and how we built around it.

Failure 2: Rule drift

Gemini knows D&D 5e in the abstract. It can quote spell descriptions and recite class features. Applying them consistently turn after turn is a different problem. Austin Amento's SoloQuest writeup documents Gemini "quietly inventing a mechanic, forgetting a restriction, or phrasing a response in a way that implied a state change that never actually happened." That is exactly why he eventually moved the rules layer into code. Gemini can't enforce rules. It can only generate text that sounds like the rules, and when the fiction wants to move forward, the fiction wins.

DungeonsDeep.ai runs on the Dungeons Deep Ruleset, an original game system, compatible with fifth edition. With a rules engine handling spell slots, conditions, advantage and disadvantage, and turn order outside the language model. The AI narrates. Code enforces.

Failure 3: The dice are not real

When Gemini "rolls" dice, it's producing a plausible looking number from its training data, not a uniform random number. A Harvard affiliated 2026 study, "Large Language Models Are Bad Dice Players", audited 11 frontier LLMs across 15 distributions and found "batch generation achieves only modest statistical validity, with a 7% median pass rate," and on independent stateless requests "10 of 11 models passing none of the distributions." Frontier models, Gemini included, all fail this test. The deeper issue is that the model can fudge a roll in either direction without telling you. If the scene wants you to succeed, the d20 lands on a 17. If it wants you to fail, it lands on a 4. No roll history, no way to verify.

In DungeonsDeep.ai, dice come from a real random number generator and every roll is logged in your session with modifiers, advantage, and crit ranges shown. You see the d20 land, you don't trust the narrator.

Failure 4: Character and inventory drift

Your character sheet is supposed to be a contract. With Gemini that contract erodes. Amento's SoloQuest writeup is the cleanest documentation we've seen: "a goblin attacking twice due to initiative state drift, defeated enemies still being described as active, spell slots being consumed in narration but not in actual game state, and death saves sounding correct but still ending up inconsistent." Every one of those is a moment where the fiction and the mechanics diverge. None of them are fixable by prompting harder.

In DungeonsDeep.ai, your character sheet is a real record, not a passage of text the model has to remember. Damage is subtracted. Items stay in your inventory until something removes them. HP, spell slots, currency, and conditions all live in state the model reads from rather than rewrites.

Failure 5: Hallucination from images

This is the Gemini specific failure mode worth naming, and it's the flip side of the feature that draws people in. Image input is one of the nicer things about Gemini, but image understanding has its own drift. A documented technical writeup shows Gemini "describing images incorrectly by missing or hallucinating details, or providing different answers about the same event depending on whether it's given a picture or text description." For a hand drawn battle map, that means the Game Master might place your party in a corridor that does not exist, miss the chest you carefully sketched in the corner, or describe the room differently from one message to the next. The map you uploaded is supposed to be the source of truth. To Gemini it's a suggestion.

In DungeonsDeep.ai, the battle map and grid live on screen as real game state. Positioning, range, and line of sight are read from the map the platform controls, not inferred from a photo the model might misread.

Failure 6: Safety filter clashes

Google's safety filters on Gemini are stricter than the rest of the category and have gotten stricter over time. Community threads on the official Google AI developer forum report Gemini 2.5 Pro filtering becoming "hypersensitive" and blocking "completely normal, safe, and SFW content." For tabletop combat involving violence, undead, body horror, or any of the tonal range a standard D&D or tabletop RPG campaign covers, you will hit refusals you would not hit on other models. A mid scene refusal does not just slow the game down. It breaks the spell.

In DungeonsDeep.ai, our human written adventures and ruleset are built for the full tonal range of tabletop play, so a goblin ambush or a crypt full of the undead runs the way the story intends instead of tripping a filter mid encounter.

Why This Happens: Gemini Is Not a Game Engine

None of these failures are because Gemini is a bad model. Gemini is a capable, friendly multimodal language model that reads images well. The problem is that running a D&D or tabletop RPG campaign is not fundamentally a language task. It's a state tracking task with a language layer on top.

A campaign needs persistent records, a real random number generator, a rules engine for damage and conditions, a map where positioning matters, and a memory of what happened in session two when you sit down for session twelve. Uploading a photo of your character sheet is not the same as having a character sheet the system can read and write. Pasting in a rulebook is not the same as running the rules. A 1M token window is impressive, but it is still a temporary scratch pad that gets discarded between conversations. The work a campaign actually needs is the work a separate game engine should be doing, with the language model handling only the narration on top.

What This Means for Your Next Session

If you want a short one shot of freeform improv that stays inside a single conversation, Gemini is fine, and it stays fun for as long as the session is small. If you want a brainstorming partner to sketch NPCs or riff on a scene, it's better than fine. If you want a real D&D or tabletop RPG campaign with real dice, persistent memory, a working battle map, and a Game Master that remembers what happened last week, you need a purpose built tabletop RPG platform.

That's the category we built DungeonsDeep.ai in. Adventures written by humans. Run by Artificial Intelligence. The platform runs on the Dungeons Deep Ruleset, an original game system, compatible with fifth edition. A separate rules engine handling mechanics, a real RNG you can verify, persistent campaign memory across sessions, a battle map and grid on screen, and structured character sheets that actually track what your party is carrying. It is free to try and currently in closed beta.

DungeonsDeep.ai in play, showing the AI Game Master, battle map, and party state during an encounter.

Frequently Asked Questions

Can Gemini really play D&D and other tabletop RPGs?

Gemini can roleplay a Game Master in a chat window for a short session, and its multimodal input lets you mix in images and documents in ways other chat tools can't. For a one shot or a few hour creative session, it works. It still can't reliably track state, enforce rules, or produce trustworthy dice rolls across a long campaign.

Can Gemini actually read my hand drawn battle map?

It can describe what it sees, and that often works for a flavor pass. It can also miss or hallucinate details, as documented in third party writeups on multimodal inconsistencies, and give different answers about the same image from one message to the next. Don't trust an uploaded map as the source of truth for your encounter geometry.

What's the best Gemini model for D&D and tabletop RPGs?

Gemini 2.5 Pro is the model most Game Masters reach for. It has the largest context window and the strongest reasoning of the Gemini lineup, which helps if you're feeding in maps and art. The faster Flash tier is cheaper and quick enough for casual play, but it tends to drift faster on rules and state. The free tier is generous enough to run a few sessions before you decide whether to pay for anything.

Is Gemini better than ChatGPT or Claude for running D&D and tabletop RPGs?

There's no clear winner. All three can read images now, all three are pleasant to play with, and each leans a little differently. Gemini handles maps, art, and rulebook screenshots smoothly and keeps a warm tone for adventures. Claude is generally considered the strongest prose voice and gives you the most room to paste in your whole campaign, while ChatGPT has the most built in tooling. None of the three solves rule drift, fake dice, or state loss, which is why purpose built platforms exist.

Why does Gemini refuse normal D&D combat scenes?

Google's safety filters are the strictest in the category and have tightened over time. Players on the official Google AI developer forum report Gemini blocking "completely normal, safe, and SFW content." For combat, undead, or body horror, the tonal range a standard campaign covers, you'll hit refusals mid scene that you would not hit on other models.

Are Gemini's dice rolls actually random?

Not really. Gemini generates plausible looking numbers from its training data rather than calling a true random number generator. A peer reviewed 2026 academic study of 11 frontier LLMs found that almost none of them passed standard randomness tests, and there's no way to verify during play that rolls aren't being shaded toward whatever outcome the scene wants.

Can Gemini run a solo D&D campaign with no other players?

Yes, and solo play is where Gemini is at its most forgiving. There's no other player to notice when an NPC contradicts itself or when a spell slot doesn't get spent. For a few sessions of solo improv with images mixed in, Gemini is genuinely fun. The failure modes still apply, they're just easier to forgive when you're the only player.

Does Gemini know the D&D 5e rules?

Gemini can quote spell descriptions, recite class features, and walk you through character creation step by step, especially if you upload the rules. What it can't do reliably is apply the rules across a long combat. Spell slots get tracked inconsistently, conditions stack incorrectly, and the order of operations shifts depending on what's narratively convenient. It knows the rules the way someone who read the books once knows them. It cannot enforce them like a game engine can.

Is there an AI Game Master that doesn't have these problems?

Yes. Purpose built platforms like DungeonsDeep.ai combine a language model for narration with a separate rules engine, a real RNG, persistent campaign memory, and a structured character sheet system. The AI handles the story. Code handles the game.

Come Find Us

If you're curious about a real AI Game Master built for D&D and other tabletop RPGs, you can sign up for our beta at dungeonsdeep.ai. Otherwise, come say hi:

This work includes material from the System Reference Document 5.2 (“SRD 5.2”) by Wizards of the Coast LLC, available at https://www.dndbeyond.com/srd. The SRD 5.2 is licensed under the Creative Commons Attribution 4.0 International License, available at https://creativecommons.org/licenses/by/4.0/legalcode.

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Playing D&D and Tabletop RPGs with Gemini (2026) | Dungeons Deep