Undercover+

The Undercover party game on a single phone, with AI-generated word pairs on any theme. Free · No sign-up · No ads · Works offline · English & French

▶ Play: trk78.github.io/undercover-plus

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🎮 How to play

One phone is passed around. Each player secretly discovers their role:

Role	Gets
🧑 Civilian	The shared secret word (e.g. Cat)
🕵️ Undercover	A close but different word (e.g. Tiger)
👻 Mr. White	No word at all: has to bluff

Taking turns, everyone describes their word in a single word, then the group votes to eliminate a suspect. Civilians win by eliminating every impostor; impostors win as soon as they are at least as many as the remaining Civilians. An eliminated Mr. White gets one last chance: guess the Civilians' word to win.

✨ Features

🤖 AI word pairs	Type a theme ("Harry Potter", "Beach"…), Gemini generates 15 original pairs, never duplicating the pack
📚 Built-in lists	3 official packs per language: Nature & Animals, Sports & Hobbies, Video Games (~50 pairs in French)
✏️ Pack editor	Create, fill and delete your own word packs
👥 Saved players	Auto avatars (colored initials) or a photo, re-import them game after game
🤫 Secret reveal	Hold the screen to see your role, release to hide it
🎲 Fair draw	Civilian / Undercover word picked at random within the pair, Mr. White never speaks first
🌍 Bilingual	Interface and words in English or French, instant switch
📦 PWA	Installable on the home screen, playable offline (except AI generation)

⚙️ How it works

The game is 100% static (vanilla HTML/CSS/JS, no framework, no build step) and lives entirely in the browser: players, packs and lobby are stored in localStorage.

Only AI generation leaves the phone. It goes through a small Cloudflare Worker that keeps the Gemini key and the prompt server-side: the key is never exposed in the front-end.

sequenceDiagram
    actor J as Player
    participant A as Undercover+<br/>(browser)
    participant W as Cloudflare Worker
    participant G as Google Gemini

    J->>A: Theme "Harry Potter"
    A->>W: POST {theme, lang, existing}
    W->>G: Prompt + key (secret)
    G-->>W: Pairs as JSON
    W-->>A: Deduplicated {pairs}
    A->>A: Add to pack (localStorage)

Loading

• The Worker tries gemini-2.5-flash, then falls back to gemini-2.5-flash-lite when overloaded (503/429).
• Responses use native JSON mode (responseSchema): no fragile parsing.
• The service worker is network-first: online you always get the latest version, the cache is only an offline fallback.

🚀 Run locally

No dependencies. All you need is a static file server (the service worker doesn't run on file://):

git clone https://github.com/trk78/undercover-plus.git
cd undercover-plus
python -m http.server 8000

Open localhost:8000. npx serve or VS Code's Live Server extension work too.

Everything works out of the box, AI generation included: it calls the public Worker set by AI_ENDPOINT at the top of script.js.

🌍 Host your own copy

1. Fork the repository.
2. Settings → Pages → Source: Deploy from a branch, branch main, folder /.
3. Deploy your own AI Worker (free Cloudflare account + free Google AI Studio key):

   cd worker
   npx wrangler login
   npx wrangler secret put GEMINI_API_KEY
   npx wrangler deploy

   Details: worker/README.md.
4. Set AI_ENDPOINT in script.js to your Worker's URL.
5. Recommended: set ALLOWED_ORIGIN in worker/wrangler.toml to your domain, then redeploy.

🗂️ Project structure

├── index.html                — Markup + every modal
├── script.js                 — Game logic, players, packs, i18n, AI call
├── data.js                   — Built-in word lists (FR / EN)
├── style.css                 — Dark theme, neon UI
├── sw.js                     — Service worker (network-first, offline)
├── manifest.json             — PWA manifest
└── worker/
    ├── undercover-plus.js    — Gemini proxy (key, prompt, model fallback, deduplication)
    └── wrangler.toml         — Cloudflare config

To add permanent lists, edit the DATABASE object in data.js:

const DATABASE = {
    "en": {
        "Nature & Animals": [["Cat", "Tiger"], ...],
        // ...
    },
    "fr": { /* ... */ }
};

⚠️ Known limitations

• AI generation needs a connection and is bound by the Worker's Gemini free-tier quota.
• Per-device data: players and packs live in the browser's localStorage, with no sync.
• English lists are shorter than the French ones (24 to 39 pairs vs ~50).

🤝 Contributing

Issues and pull requests are welcome: open an issue. Keep the project's spirit: vanilla, no framework, no build step.

Open ideas:

• preview AI pairs before adding them;
• replace alert / confirm / prompt with modals;
• score tracking across rounds;
• longer English lists.

📄 License

MIT © Timéo Jeannin