Millbrook runs directly against Anthropic's Claude API. You will need your own key. It takes about two minutes to set up and includes a small free credit to start with.

1. 1Go to console.anthropic.com and create a free account.
2. 2Once logged in, click API Keys in the left sidebar.
3. 3Click Create Key, give it a name, and copy the key. You will not see it again.
4. 4Paste it into the field above and click Connect.

// Your key never leaves your browser. It is stored in localStorage on your device only, and is sent nowhere except directly to Anthropic's API during gameplay. Never share your API key publicly. You can track approximate usage via the Usage button above; for accurate costs and full history, check your Anthropic console.