🎭 LeoMafia: Zero-Knowledge Blockchain Mafia Game

🚀 Overview

LeoMafia is a revolutionary implementation of the classic Mafia party game built on the Aleo blockchain using the Leo programming language. This project combines the strategic gameplay of traditional Mafia with cutting-edge zero-knowledge proofs and decentralized smart contracts to create a trustless, verifiable, and privacy-preserving gaming experience.

🌟 Innovation Highlights

🔐 Zero-Knowledge Privacy

• Hidden Role System: Player roles are cryptographically committed using BHP256 hash functions
• Private Detective Investigations: Investigation results are revealed only to the detective using ZK proofs
• Confidential Night Actions: Mafia votes and Angel protections remain private until resolution

⛓️ Blockchain Integration

• Smart Contract Game Logic: All game mechanics implemented in Leo smart contracts
• Immutable Game State: Game progression and results stored on-chain
• Cryptographic Randomness: Secure role assignment using blockchain-based entropy
• Stake-Based Participation: Players commit tokens to participate, while voting for mafia, creating economic incentives

🎮 User Flow: From Joining to Winning

🛠️ Game Initialization

• A player or game host deploys a new game instance via the Leo smart contract.
• A unique

  game_id

  is assigned and broadcasted on-chain.

👥 Joining the Game

• Players connect their Aleo wallets via the frontend (built with Next.js + TypeScript).
• They stake tokens to enter the game, which also acts as their commitment.
• Upon joining, each player is assigned a role (Villager, Mafia, Detective, Angel), which is:
  • Cryptographically committed using BHP256 hashing
  • Stored privately using a zero-knowledge commitment

🌙 Night Phase Mechanics

Players with special roles perform secret actions via ZK proofs:

• 🗡️ Mafia selects a player to eliminate.
• 🔍 Detective investigates one player. The result is shown only to them via ZK proof.
• 🛡️ Angel selects a player to protect from elimination.

All night actions are submitted as zero-knowledge transactions, where both inputs and results are hidden but cryptographically verifiable.

☀️ Day Phase & Voting

• Surviving players vote to eliminate a suspected Mafia member.
• Votes are:
  • Secured via zero-knowledge proofs
  • Committed on-chain using hashed commitments
• Optional vote staking increases the weight of a vote, encouraging stronger commitment.

🔄 Game Progression & Elimination

• The backend tracks time-locked phases using mappings.
• Game transitions automatically between night and day.
• Eliminated players are updated on-chain, but their roles remain secret.
• The game continues until one side (Mafia or Village) fulfills their win condition.

🏆 Game Conclusion & Rewards

• Once victory conditions are met (e.g., all Mafia are eliminated), the game ends.
• Roles are revealed, and the reward pool is automatically distributed to the surviving winning team.
• Distribution is handled fully on-chain using Leo logic.

⚙️ Technical Flow

1. Smart Contract Mechanics (Leo)

• Player Record: Each player has a smart contract record containing owner, role, game_id, stake, and is_alive.

• Role Privacy: Roles are hashed using BHP256 and stored in a

  role_commitments

  mapping.

• Phase Timing:

  round_deadline

  mapping handles deadlines for each phase, ensuring fair progression.

• Game Logic: All player actions (investigation, vote, protect, kill) are implemented as verifiable private functions using ZKPs.

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2. Frontend Infrastructure

• Built using Next.js and TypeScript, interfaced with Leo CLI and the Aleo blockchain.

• Connects directly to the Leo Wallet for transaction signing and role verification.

• Implements real-time state polling to reflect game events and updates via on-chain reads.

• Displays cryptographic operations (like proofs, commitments, hashes) in an intuitive format for players.

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3. ZK Proof Usage

• Detective Results: Players submit a proof to validate another’s role without revealing their own.

• Vote Validation: Votes are cast as commitments; tallying is done through ZK aggregation.

• Protection and Kill Logic: Intersecting ZK operations determine if a Mafia kill was blocked by the Angel.

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4. Economic Design

• Stake to Join: Each player deposits a stake, which forms the reward pool.

• Vote Staking: Additional tokens can be staked to back a vote (e.g., higher conviction = higher weight).

• Reward Distribution: On game completion, the prize pool is auto-distributed to the surviving winning team.