AI Dungeon was one of the first consumer games built on a large language model. Created by Nick Walton, then in a deep-learning lab at Brigham Young University, it used OpenAI’s GPT-2 to act as an endlessly improvising dungeon master: the player types an action in plain English and the model writes what happens next, so the story can go anywhere rather than down a pre-authored branch.
The first version appeared in early 2019. The breakthrough came with AI Dungeon 2, which Walton described in his own write-up dated November 21, 2019. There he explained that they “upgrade the size of our model to OpenAI’s largest 1.5B parameter model” and fine-tuned it “on a collection of text adventures obtained from chooseyourstory.com.” Crucially, AI Dungeon 2 would “do away with pregenerated actions and allow the user to enter any action,” realizing the vision of “an infinitely generated world that you could explore endlessly, continually finding entirely new content and adventures.”
The game went viral, drawing roughly 100,000 players within a week and passing a million by early 2020. Walton founded the studio Latitude to run it. AI Dungeon also became an early lesson in the realities of generative play - the model could lose track of “who is who, especially in dialogue,” and the open-ended nature later forced hard questions about moderation and content filtering. It stands as a pioneering demonstration that an LLM could be the engine of an interactive game.