Turtle 🐢

A daily word puzzle game built with vanilla JavaScript and Bitcoin Lightning payments for unlimited gameplay.

Play the live game: https://turtlewordgame.xyz

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Features

• Daily Word Puzzle — Guess the 5-letter word in 6 attempts
• 14 Languages — Afrikaans, Dutch, English, French, German, Italian, Polish, Portuguese, Spanish, Swahili, Turkish, Vietnamese, Xhosa, Zulu
• Bitcoin Lightning Payments — One free game per day, with Lightning Network payments for unlimited play
• Global Leaderboard — Compete with players worldwide
• Nostr Integration — Share your results on the decentralized social protocol
• Mobile-First Design — Fully responsive with touch-optimized keyboard
• Accessible — Keyboard navigation, ARIA labels, reduced motion support

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How to Play

1. Open https://turtlewordgame.xyz
2. Select your preferred language from the dropdown
3. Type a 5-letter word using your keyboard or on-screen keys
4. Press Enter to submit your guess
5. Use the color feedback to narrow down the word:
   • Green — Letter is correct and in the right spot
   • Yellow — Letter is in the word but wrong position
   • Gray — Letter is not in the word
6. Solve the puzzle in 6 guesses or fewer!

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Running Locally

Prerequisites

• Node.js 18+
• npm

Setup

# Install dependencies
npm install

# Create environment file for Lightning payments
cp .env.example .env
# Add a Nostr Wallet Connect (NIP-47) connection string:
# NWC_URL=nostr+walletconnect://<pubkey>?relay=wss://...&secret=<hex>

# Start the server (Vercel CLI runs the /api functions locally)
npm start

The game will be available at http://localhost:3000.

Getting an NWC_URL

Any NWC-capable wallet issues one — Alby Hub, Coinos, LNbits, Zeus, and others. In Alby Hub it's under Connections → Add Connection.

Scope the connection to make_invoice and lookup_invoice only. This secret sits on a web server, so it must not be able to spend: never grant it pay_invoice. Worst case, a leaked key lets someone generate invoices that pay you.

Because the app speaks NIP-47 rather than a vendor API, switching wallets later means changing NWC_URL and nothing else.

For local testing without real sats, curl -X POST 'https://faucet.nwc.dev?balance=50000' returns a working throwaway connection string on a fake-sats network.

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Project Structure

turtle/
├── index.html          # Main HTML with all modals
├── script.js           # Game logic, API calls, Nostr integration
├── style.css           # Styling with responsive design
├── package.json        # Dependencies and scripts
├── api/
│   ├── _nwc.js            # Shared NWC client + connection lifecycle
│   ├── create-invoice.js  # Lightning invoice generation
│   └── check-invoice.js   # Payment verification
└── words/
    ├── english.txt     # 5-letter word lists by language
    ├── french.txt
    ├── german.txt
    └── ...             # 14 language word lists

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API Endpoints

Both endpoints talk to your wallet over Nostr Wallet Connect (NIP-47), using the make_invoice and lookup_invoice methods.

Endpoint	Method	Description
/api/create-invoice	POST	Creates a Lightning invoice via NWC
/api/check-invoice	GET	Checks payment status by hash

Create Invoice

curl -X POST http://localhost:3000/api/create-invoice \
  -H "Content-Type: application/json" \
  -d '{"amount": 100, "memo": "Turtle Game Payment"}'

Response:

{
  "paymentHash": "abc123...",
  "paymentRequest": "lnbc100...",
  "satoshis": 100
}

Amounts are whole sats between 1 and 1,000,000; invoices expire after 10 minutes.

Check Invoice

curl "http://localhost:3000/api/check-invoice?paymentHash=abc123..."

Response:

{
  "paid": true,
  "status": "settled"
}

paid is the field to trust. NIP-47 treats status as optional, so it is derived from the invoice's settlement timestamp and preimage rather than reported state.

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Technology Stack

Layer	Technology
Frontend	Vanilla JavaScript, HTML5, CSS3
Backend	Node.js 22+ (Vercel serverless functions)
Payments	Bitcoin Lightning Network via Nostr Wallet Connect (NIP-47)
Social	Nostr Protocol
Fonts	Clear Sans, Helvetica Neue

External Dependencies

• WebLN (v0.3.2) — Browser Lightning wallet integration
• QRCode (via CDN) — QR code generation for invoice payments
• @getalby/sdk — NWC client for server-side invoice creation and lookup

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Keyboard Shortcuts

Key	Action
A-Z	Type a letter
Enter	Submit guess
Backspace	Delete last letter

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Game Rules

• One free game per 24-hour period (resets at midnight UTC)
• Additional games require a 100 satoshi Lightning payment
• Word must be exactly 5 letters
• For English, guesses must be valid dictionary words
• Statistics tracked: games played, win rate, current streak, max streak

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Contributing

1. Create a feature branch (git checkout -b feature/amazing)
2. Commit your changes (git commit -m 'Add amazing feature')
3. Push to the branch (git push origin feature/amazing)
4. Open a Pull Request

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License

MIT License — feel free to use, modify, and distribute.

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Acknowledgments

• Lightning payments powered by Nostr Wallet Connect (NIP-47)
• Social sharing powered by the Nostr protocol
• Created by jasonb on Stacker News