Hi HN — I built “Undefined”, a live multiplayer text world where an LLM acts as a “reality referee” (not a friendly chatbot).

Demo: https://undefinedai.xyz/

Notes: - No signup required - BYOK supported (bring your own API key/model) - Server-funded guest usage is capped (~$20) to avoid runaway costs - /do is concurrency-limited so the server stays stable under traffic

Tech/how to play: https://github.com/pearl-100/undefined-public

Write-up: https://open.substack.com/pub/undefinednamoo/p/i-spent-200-t...

2-min demo video: https://www.youtube.com/watch?v=q-B4f1oEzfw