Aleo Tiktactor — Private Tic-Tac-Toe on Aleo

A real, working Tic-Tac-Toe game implemented in Leo (the language for Aleo) with a tiny TypeScript host that submits moves and reads the on-chain state.

The game uses Aleo's zero-knowledge proofs to keep the board private: the contract doesn't know which cell each player chose, only the final result after a winner check.

This is not a placeholder. The Leo program compiles (with leo build) and the host script calls the deployed program on the Aleo testnet.

Stack

• Leo 1.6+ — the program
• @aleohq/sdk 0.9+ — the host (TypeScript)
• Aleo testnet — for the deployed instance

Layout

.
├── program/                  # the Leo source
│   ├── program.json
│   ├── src/
│   │   └── main.leo
│   └── build/                # created by `leo build` (gitignored)
├── host/                     # TypeScript host
│   ├── package.json
│   ├── tsconfig.json
│   ├── src/
│   │   ├── index.ts
│   │   ├── play.ts
│   │   └── reveal.ts
└── README.md

Run

# 1. Build the Leo program
cd program
leo build

# 2. Deploy to testnet
leo deploy --network testnet

# 3. Play from the host
cd ../host
npm install
npm run play -- --player alice --cell 4
npm run play -- --player bob   --cell 0
npm run reveal -- --game 1

How the privacy works

The contract stores the board as 3 record fields (one per row). Each player submits a Move record, the contract adds it to the board, and proves in zero-knowledge that:

• Each move was a valid (cell 0..8, empty)
• The same cell wasn't taken twice
• A winner is correctly reported (or not)

The host never sees the opponent's move — only the public winner result.

Why Tic-Tac-Toe?

Smallest non-trivial game. Demonstrates the pattern: private state + public result, which is the basis for private DeFi (dark pools, sealed-bid auctions, …).

License

MIT