Accidental Discovery Leads to Custom Pet Creation
Simon Willison recently stumbled upon a feature in Codex Desktop that he had overlooked since its announcement in May. He accidentally activated a pet, a small animated robot reminiscent of Clippy, and then discovered that users can create their own custom pets.
Willison decided to make his own pet and ended up with a cute little pelican on a bicycle that bounces around his desktop and provides updates on his Codex tasks. The pet is called Pedalican, a name generated by GPT-5.6 Sol.
How the Custom Pet Was Made
The most interesting part of the process for Willison was watching how the custom pet was created. He told the system he wanted a custom pet that was a pelican riding a bicycle. GPT-5.6 Sol xhigh handled the rest of the work, using several rounds with gpt-image-2 to generate the necessary sprite assets.
Willison had the system make extensive notes and record all intermediary steps. His GitHub repository includes every generated image and combined sprite sheet, plus GIFs for each of the animation loops. One example is waving.gif, which was compiled from a single image generated by gpt-image-2.
That single image was created by executing a prompt against the initial generated character reference image. The character reference image was created with a prompt that has a specific structure. The prompt reads: "Create one clean full-body reference sprite for Codex pet Pedalican. Pet identity: A compact adorable baby pelican with a round cream-white body, soft coral-orange bill and feet, riding a tiny sky-blue bicycle. Place a single centered pose on a perfectly flat pure magenta #FF00FF chroma-key background. Keep the full pet visible, compact, readable at 192x208, and easy to animate."
Stay ahead of the AI curve
The most important updates, news, and content — delivered weekly.
No spam. Unsubscribe anytime.
Open Source Implementation Details
Willison has been looking for examples of ways to use image generation to create simple game-ready sprites. He spent some time digging into the mechanism to see how it works. The key implementation details are open source, specifically two skills that are both Apache 2.0 licensed.
Willison noted that GPT-5.6 Sol came up with the name "Pedalican" and he likes it. The entire project is documented on his GitHub repo, including all generated images and animation loops.
Background on Codex Desktop
Codex Desktop is a development environment that integrates AI capabilities. The pet feature allows users to have animated characters that provide updates on tasks. The ability to create custom pets opens up new possibilities for personalization and creative expression within the platform.
Willison's experiment demonstrates how AI image generation tools can be used to create game-ready sprites with minimal manual effort. The process involved multiple rounds of generation and refinement to produce the final sprite assets.