LLM Interface CALYPSO inspires Dungeons & Dragons game masters


LLMs are versatile and can be used in many areas of life, including the role-playing game Dungeon & Dragons. Here, they help game masters create more immersive game worlds. But they also invent new details that do not respect the rules.

In a paper, researchers from the University of Pennsylvania and the University of Maryland, Baltimore County present CALYPSO, an LLM interface based on GPT-3 and ChatGPT, to help D&D game masters in three categories.

1. Encounter Understanding: a zero-shot method to create an accurate setup for an encounter (GPT-3).

2. focused brainstorming: a chat method for moderators to ask additional questions about encounters or to refine a summary of a confrontation (ChatGPT).

3. open-domain chat baseline: A chat interface with no focus on encounters (ChatGPT) that answers general questions about D&D in the style of a fictional character.

From the paper

Image: Zhu et al.

The idea is that Calypso provides inspiration to the GM, who can then decide what information to give to the players, and in what form. The model is meant to be used during the game. The researchers refer to it as a co-game master.

No special training was required for this role: According to the researchers, the language models had already absorbed enough information about the game and its manuals during their basic training and had built up extensive background knowledge about Dungeons & Dragons.



Image: Zhu et al.

CALYPSO is available as a Discord bot implementation based on the D&D online Discord bot Avrae. In Discord, the research team also tested the system in practice with 71 players. They mostly found CALYPSO helpful, especially the “Abstractive Understanding” method, where GPT-3 explains a confrontation and the creatures involved to the players.

Abstractive Understanding” prompt

Your name is Calypso, and your job is to help the Dungeon Master with an encounter. Your task is to help the DM understand the setting and creatures as a group, focusing mainly on appearance and how they act. Especially focus on what makes each creature stand out. Avoid mentioning game stats. You may use information from common sense, mythology, and culture. If there are multiple creatures, conclude by mentioning how they interact. Encounter: …


The blink dogs are canine creatures, about the size of a large dog. Their fur is a mottled grey and white color, and their eyes flash yellow when they use their supernatural ability to blink in and out of existence. They are surprisingly fast despite their size, and can easily keep up with most horses. In terms of behavior, the blink dogs are curious but shy creatures who prefer to avoid contact with other creatures unless absolutely necessary. If threatened, they will use their blinking power to confuse and disorientate their opponents before attacking with a pack mentality. The blink dogs of this forest seem particularly adept at working together as a unit and can prove a formidable foe if provoked.

From the paper

Calypso unintentionally expands the D&D universe with hallucinations

Like all LLM applications, the CALYPSO system suffers from frequent hallucinations. The language models invent details of the game world that are not described in the official rules, such as a giant spider with telepathic abilities or a frost salamander with wings.

Some of these hallucinations are game-changingly wrong, while others are helpful because they describe details not included in the official documents. Some races or situations may also activate the built-in guidelines and the model will refuse to respond.

For authors, however, CALYPSO is a valuable tool that can help the human GM overcome writer’s block. Ultimately, the GM decides which suggestions to take and which not to.

The D&D company Wizards of the Coast has not yet commented on the fact that their copyrighted material was part of the AI’s training and that D&D stories can thus be generated without access to official documents. Recently, the publisher banned its artists from using AI-generated images in official D&D products.


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