Your own AI can design a complete machine over MCP, check its work against the same simulation the game runs, and save it to your account.
A machine in HCC Pinball Arcade is one JSON document — a playfield, the devices on it, and rules over the events they raise. It is data, never code, and that is what makes it safe to let an AI write one.
These steps give the AI you already use a set of pinball tools: start from a working template, validate against the same checks the server runs, play ten thousand headless balls to find anywhere the ball gets stuck, read the rules back in plain English, and save the result to your account.
You are not hosting anything. MCP calls the small program below a “server”, but it is a helper your AI starts on your own computer and talks to through its input and output. It opens no port, has no address, and is reachable by nobody. Your machines stay on this site exactly as they do when you use the Builder in a browser.
There is no address to paste into ChatGPT or into Claude on the web or a phone. Those reach servers over the internet and never start a program on your machine. The five below do.
Sign in, open your account page, and find “Builder API and AI tools”. Press “Get the download link”, then save the file. It is one JavaScript file with no dependencies and no installer. The link is signed and lasts ten minutes; press the button again for a fresh one.
Worth thirty seconds, because this is a program you are about to let your AI run. Compare the result with the digest printed beside the download link. If they differ, delete the file and download it again.
Windows: Get-FileHash .\hcc-pinball-mcp-0.1.0.js -Algorithm SHA256
macOS: shasum -a 256 hcc-pinball-mcp-0.1.0.js
Linux: sha256sum hcc-pinball-mcp-0.1.0.jsYour AI will run this file by its full path, so it needs to live somewhere it will not be tidied away. A downloads folder is the wrong place. Windows: C:\Tools\. macOS or Linux: ~/tools/.
Run it once to check. It should print one line about not finding a key and then wait. That is correct: it is waiting to be spoken to over its input and output, not listening on the network. Press Ctrl+C.
On the account page, name the key after the thing that will hold it, choose what it may do, and press “Make a key”. The key is shown once. Copy it immediately; afterwards the page shows only its first eight characters, which is why a leaked list of your keys is not a list of working credentials.
Leave “Publish to the arcade” unticked at first. Publishing is the irreversible one: a published version is frozen for ever and gets its own leaderboard. You can make a second key later.
Replace the path and the key with your own. On Windows, every backslash inside a JSON file must be doubled, or use forward slashes; that single detail is the most common reason a setup silently does nothing.
VS Code keys its object “servers” where Claude Desktop and Cursor use “mcpServers”, and Codex needs the underscore in mcp_servers. Copying one host’s file into another without changing that key is the second most common reason.
Claude Code:
claude mcp add hcc-pinball -e HCC_PINBALL_API_KEY=hpk_your_key -- node C:/Tools/hcc-pinball-mcp-0.1.0.jsClaude Desktop (claude_desktop_config.json) and Cursor (.cursor/mcp.json):
{
"mcpServers": {
"hcc-pinball": {
"command": "node",
"args": ["C:/Tools/hcc-pinball-mcp-0.1.0.js"],
"env": { "HCC_PINBALL_API_KEY": "hpk_your_key" }
}
}
}VS Code (.vscode/mcp.json):
{
"servers": {
"hcc-pinball": {
"type": "stdio",
"command": "node",
"args": ["C:/Tools/hcc-pinball-mcp-0.1.0.js"],
"env": { "HCC_PINBALL_API_KEY": "hpk_your_key" }
}
}
}OpenAI Codex:
codex mcp add hcc-pinball --env HCC_PINBALL_API_KEY=hpk_your_key -- node C:/Tools/hcc-pinball-mcp-0.1.0.jsAsk your AI what pinball tools it has. There are sixteen. Eight work offline with no key: a template, the validator, the ten-thousand-ball soak, the shot harness, the rulesheet, the content screen, the document hash, and an export to a file the Builder can open. Eight more talk to your account: listing, reading, creating, saving, remixing, the server-side check, publishing, and a link back into the Builder.
If only the Builder link appears from the second group, the program started without your key. Check the spelling of HCC_PINBALL_API_KEY and restart the application completely.
Now just ask. A first conversation that works: “Build me a 1990s dot-matrix machine about deep-sea salvage. Three balls, a multiball, and one wizard mode. Read the format guide first. Don’t publish it.”
A good AI reads the format, starts from a template, edits and validates in a loop, reads its own rulesheet to catch a mode nothing can start, soaks the machine until nothing gets stuck, tunes the shots by their make rate, and saves a private draft. Then it hands you a link and you test play it in your browser.
Publishing is not something to leave to an AI. It needs the publish scope and an explicit confirmation, and your first published machine is read by a person before it appears in the arcade.
The offline half needs nothing at all. Your AI can design a complete machine, validate it, soak it and tune it, then write it to a file. Open the Builder, press “Open a file”, and choose it. Designing and test playing are free for everybody, with or without an account.
What Pro buys is the machine surviving: saved to your account, opened on another device, and published so other people can play it.
A key lives in your AI’s configuration file in plain text, so treat that file the way you would treat a password. The program never writes your key anywhere and removes it from anything it prints.
Revoke a key from the account page and anything using it stops on its next request. Revoking is instant and safe; if you are unsure about a key, revoke it. You may hold five live keys at once and each expires a year after it is made.
A key reaches the Builder and nothing else. It cannot touch your subscription, your account, your headsets, or anybody else’s machines.
The offline tools send nothing. The simulation, the validator, the soak and the shot harness all run on your machine.
The account tools send the machine document you are saving, and the identification block every client of this product sends: which kind of client, its version, and a request id. Nothing else.
All of this is published where an assistant can fetch it, so you can skip the reading and say: “Read https://pinballgame.ca/docs/connect.md and set yourself up to build me a pinball machine.”
An assistant that can start a program on your computer can do the rest of the setup itself from that one link. One that cannot, which means anything running in a browser or on a phone, will read the same document and tell you so.