Onchain Games Contracts

A modular smart contract system for onchain gaming with support for multiple game types, leaderboards, and jackpots. Currently available on Cronos chain and BSC Chain (Binance Smart Chain/ BNB Chain).

Architecture

┌─────────────────────────────────────────────────────────────────────────────┐
│                           OnchainGameManager                                │
│                     (Central registry & game creation)                      │
└─────────────────────────────────────────────────────────────────────────────┘
                    │                    │                    │
                    ▼                    ▼                    ▼
    ┌───────────────────┐  ┌───────────────────┐  ┌───────────────────────┐
    │ OnchainGameEarnings│  │OnchainGameLeaderboard│  │   Game Contracts     │
    │   (Fund mgmt)      │  │  (Rankings/Jackpot) │  │ (MultiplierWithScore,│
    │                    │  │                     │  │   ScratchCard, etc)  │
    └───────────────────┘  └───────────────────┘  └───────────────────────┘

Contracts

Contract	Description
OnchainGameManager.sol	Central registry for games and game types
OnchainGameEarnings.sol	Handles player earnings, house funds, and fee distribution
OnchainGameLeaderboard.sol	Manages player rankings and jackpot distribution
MultiplierWithScoreGame.sol	Two-phase game: draw multiplier → apply score
ScratchCardGame.sol	Single-phase instant win scratch card game
TestToken.sol	ERC20 token for testing
TokenWhitelist.sol	Token approval registry

Installation

npm install

Compile

npx hardhat compile

Test

npx hardhat test

Deploy (localhost)

Start a local node:

npx hardhat node

Deploy contracts:

npx hardhat run scripts/deploy.js --network localhost

Game Flow

MultiplierWithScoreGame (Two-Phase)

1. Phase 1 - playGame(): Player bets tokens, draws a random multiplier (0.8x, 1.2x, 1.8x, or 3x)
2. Phase 2 - endGame(): Player submits score (0-100), final earnings = bet × multiplier × score / 100

ScratchCardGame (Single-Phase)

1. playGame(): Player bets tokens, instantly reveals win/lose result with multiplier

Multiplier Distribution

Multiplier	Probability
0.8x	70%
1.2x	20%
1.8x	8%
3.0x	2%

Fee Structure

• Owner Fee: 10% of each bet
• Jackpot Contribution: 5% of each bet
• House Funds: 85% of each bet (for payouts)

License

MIT