Sep 11, 2025 14:02:00

'Animal Crossing LLM Mod' replaces the dialogue of GameCube's 'Animal Crossing' with AI-generated dialogue

Developer Josh Fonseca has developed the Animal Crossing LLM Mod ,

a mod that uses a large-scale language model (LLM) to generate real-time conversations between the residents of Animal Crossing for the Nintendo GameCube. This mod doesn't modify the game's source code at all, but instead directly manipulates the memory of the GameCube emulator Dolphine .

I Replaced Animal Crossing's Dialogue with a Live LLM by Hacking GameCube Memory
https://joshfonseca.com/blogs/animal-crossing-llm

GitHub - vuciv/animal-crossing-llm-Mod: AI-powered dialogue generation for Animal Crossing villagers using LLMs
https://github.com/vuciv/animal-crossing-llm-Mod

I Replaced Animal Crossing's Dialogue with a Live LLM by Hacking GameCube Memory
https://simonwillison.net/2025/Sep/10/animal-crossing-llm/

The Animal Crossing LLM Mod uses a Python script to constantly monitor the memory of Animal Crossing running on Dolphin. When a conversation with a resident begins, the name of the character speaking and the content of the conversation are read from memory. This information is then sent to an external LLM such as Google Gemini or OpenAI, which generates new dialogue based on the character's personality and the context of the conversation.

The generated text is not just a string of characters, but is encoded into a format that includes special control codes that specify the end of the conversation in Animal Crossing, pauses, text color, character expressions, etc. This encoded data is written directly into the game's memory, allowing the AI-generated conversation to appear natural in the game.

Since it takes a few seconds for the LLM to respond, it is not possible to instantly replace the dialogue. To solve this problem, the mod first writes a control code into memory that pauses the game for a few seconds. This allows the LLM to generate a response, and once it is complete, it replaces the dialogue with the new content.

You can see in the movie below how the Animal Crossing LLM Mod is actually running and having the residents of 'Animal Crossing' talk to each other using LLM.

I Replaced Animal Crossing's Dialogue with AI by Hacking GameCube Memory - YouTube


The Animal Crossing LLM Mod consists of two LLMs: a 'writer' who creates creative dialogue, and a 'director' who adds poses, expressions, etc. to the dialogue. Writers are given character personality sheets obtained from fandom wikis created by volunteers, as well as information from external news feeds, to generate deeper conversations.

Apparently, this system has led to residents starting to talk about current events.

The video also shows residents remembering past conversations and gossiping about

Tom Nook 's business practices, urging them to rebel. The source code also apparently includes a prompt to help residents realize that the loans Tom Nook offered them were exploitative.

The full code for this project is available on GitHub. However, it is experimental software and currently only supports macOS. Fonseca welcomes contributions from the community, including bug fixes, support for Windows and Linux, and improvements to memory read stability.