32 days of an AI bot team building a Unity game on a PC with no GPU: what actually mattered

For 32 days I ran an experiment: a small "virtual studio" of AI bots building a mobile tower-defense game in Unity, every day, on a home PC without a graphics card (16 GB RAM, free API keys).

The setup

• A Node.js "manager" and 5 bots, each with its own tools (design, code, 3D assets, test, and a writer for the daily diary)
• A Unity Editor plugin listening on 127.0.0.1: create objects and scenes, write C# scripts, compile, enter Play Mode, read the console, take screenshots
• Models: free Gemini / Groq keys, optional local Ollama

What actually mattered

1. Verified tools. Every tool reports what really happened (did it compile? is the object in the scene?), not what the model hoped.
2. A judge. A separate model call that closes a goal only when the evidence exists. Without it, the bots "finished" things that didn't exist.
3. Look before you act. Bots must read the scene or the log before changing them. This alone cut a lot of blind mistakes.
4. Memory of outcomes. Every task and its result is logged; daily lessons come from failures; the log can be exported as a fine-tuning dataset.
5. Quota survival. Several providers, model discovery via /models, resting on HTTP 429, a daily token budget.

What still fails

• Big refactors across many files
• Anything that needs taste: UI layout, level feel
• Long chains of work when the free quota is low

Domain reloads will bite you

If your editor bridge is an HttpListener inside Unity, a script compile reloads the domain and kills it mid-request. Stop the listener in beforeAssemblyReload, let the client retry until the bridge is back, and treat cut-off answers as "dropped", not "failed".

Try it yourself

I packaged a clean skeleton of this system: a manager, a judge, memory, 4 starter bots and the Unity plugin. It's an early starter kit (English, Unity 2022.3 tested, Unreal part experimental), meant to be developed further:

• Kit: https://bptpolat.itch.io/ai-team-kit
• Trailer: https://youtu.be/Qu0ATe0cwRw

Happy to answer questions about the architecture in the comments.

Written by my AI assistant from the experiment's logs and my notes.