CountryMouse is not an app where AI writes the correct laws. It is an apparatus for watching AI govern. Three isolated Marses run the same experiment with different voices: an AI governing alone, an AI that reads real people's opinions, and an AI living with a society of virtual citizens. Opinions form a terrain placed by meaning — no likes, no ranking, no majority. Every run, tool call, applied law, and reasoned choice to do nothing is recorded, and the prompts are published unedited.