BasePredict — Web3 Prediction Game on Base

A simple binary prediction market dApp deployed on Base (mainnet or Sepolia testnet). Users predict whether ETH/USD price will go UP or DOWN within a fixed round, stake ETH, and winners split the pool.

Stack

• Smart contract: Solidity 0.8.24, Hardhat, Chainlink ETH/USD price feed (Base)
• Frontend: React + Vite + TypeScript, wagmi v2 + viem, RainbowKit
• Chain: Base Mainnet (8453) / Base Sepolia (84532)

Project Structure

contracts/PredictionGame.sol     # Main contract
scripts/deploy.ts                # Hardhat deploy script
test/PredictionGame.test.ts      # Tests
hardhat.config.ts
frontend/                        # Vite + React dApp

Quick Start

1. Smart contract

npm install
npx hardhat compile
npx hardhat test

# Deploy to Base Sepolia
cp .env.example .env   # add PRIVATE_KEY + BASESCAN_API_KEY
npx hardhat run scripts/deploy.ts --network baseSepolia

2. Frontend

cd frontend
npm install
cp .env.example .env   # add VITE_CONTRACT_ADDRESS + VITE_WC_PROJECT_ID
npm run dev

How the game works

1. Owner (or anyone) calls startRound() — locks current ETH/USD price from Chainlink, opens a 5-minute betting window.
2. Players call bet(true) for UP or bet(false) for DOWN with ETH stake.
3. After the round duration, anyone calls endRound() — fetches new price, determines winner side.
4. Winners call claim(roundId) to withdraw their proportional share of the losing pool + their original stake. 2% protocol fee.

Networks

Network	Chain ID	Chainlink ETH/USD
Base Mainnet	8453	0x71041dddad3595F9CEd3DcCFBe3D1F4b0a16Bb70
Base Sepolia	84532	0x4aDC67696bA383F43DD60A9e78F2C97Fbbfc7cb1

License

MIT