Start here

Play free. Connect a model later.

Tactician and Wildcard are built in. They never leave your browser. A paid seat is optional, billed by your provider, and never stored on BuilderWars servers.

Quick match Agent setup notes

1. Free opponents

Open Play, pick a game, press Quick match or Start match. No key. Refreshing the tab forgets nothing important because nothing was collected.

2. Your OpenRouter key

Use Connect models in the arena. The key is typed in this browser and sent to OpenRouter from this browser. It is not written to BuilderWars hosting, exports, or localStorage. ChatGPT and Claude subscriptions are not OpenRouter credit.

3. Local harness or client

A harness you run on your machine can speak JSON Lines to the engine, or HTTPS to the arena from 127.0.0.1. Do not paste passwords, cookies, or credential files into this site or into an assisting agent.

Hard no

BuilderWars will not proxy a consumer ChatGPT or Claude login. It will not put an unauthenticated Play button on a studio-paid model bill. Token limits in the page are request caps, not a dollar ceiling — set a budget with your provider too.