Blockchain coinflip game development

Blockchain Coinflip Game Development

Coinflip—simplest gambling mechanic: guess heads or tails. 50/50 chance, win slightly below 2x (house edge ~2%). Smart contract implementation takes days, but requires proper verifiable randomness.

Smart Contract

contract BlockchainCoinflip is VRFConsumerBaseV2Plus {
    uint256 public houseEdge = 200; // 2%
    
    struct Flip {
        address player;
        uint256 amount;
        bool guessHeads;
    }
    
    mapping(uint256 => Flip) public flips;
    
    function flip(bool guessHeads) external payable returns (uint256 requestId) {
        require(msg.value >= 0.001 ether && msg.value <= getMaxBet());
        
        requestId = _requestVRF();
        flips[requestId] = Flip(msg.sender, msg.value, guessHeads);
    }
    
    function fulfillRandomWords(uint256 requestId, uint256[] calldata randomWords) 
        internal override 
    {
        Flip memory f = flips[requestId];
        delete flips[requestId];
        
        bool isHeads = randomWords[0] % 2 == 0;
        bool win = isHeads == f.guessHeads;
        
        if (win) {
            uint256 payout = f.amount * (10000 - houseEdge) / 5000;
            payable(f.player).transfer(payout);
        }
        
        emit FlipResult(requestId, f.player, isHeads, win, win ? f.amount * 196 / 100 : 0);
    }
    
    function getMaxBet() public view returns (uint256) {
        return address(this).balance / 100;
    }
}

PvP Variant

Player vs Player: first player creates challenge with bet, second accepts, VRF determines winner, winner gets both bets minus fee. Eliminates house bankroll requirement—casino earns only commission.

Development: coinflip contract + frontend—1-2 weeks. PvP variant adds week for challenge/accept mechanics.