Ethereum DAPP for playing Rock, Paper, Scissors. Created using remix-ide: Realtime Ethereum Contract Compiler and Runtime. Load this file by pasting this gists URL or ID at https://remix.ethereum.org/#version=soljson-v0.4.24+commit.e67f0147.js&optimize=false&gist=

RPS.sol

pragma solidity ^0.4.23;

contract RPS {
    
    address player1;
    address player2;
    
    bytes32 commitment;
    string play1;
    string play2;
    
    uint stake;
    
    bytes32[] moves;
    
    function RPS() public payable {
        player1 = msg.sender;
        
        moves.push(keccak256("Rock"));
        moves.push(keccak256("Paper"));
        moves.push(keccak256("Scissor"));
    }
    
    function p1_commit(bytes32 _commitment) public payable {
        require(msg.sender == player1);
        require(msg.value > 0 ether);
        
        commitment = _commitment;
        stake = msg.value;
    }
    
    function p2_join(string _play) external payable {
        require(_strEmpty(play2));
        require(_validMove(_play));
        require(msg.value == stake);
        
        play2 = _play;
    }
    
    function p1_reveal(string _play, string _salt) external {
        require(msg.sender == player1);
        require(keccak256(_play, _salt) == commitment);
        require(_validMove(_play));
        
        play1 = _play;
    }
    
    function p2_payout() external {
        require(msg.sender == player2);
    }
    
    function p1_replay(bytes32 _commitment) external {
        require(msg.sender == player1);
        commitment = _commitment;
    }
    
    function p2_replay(string _play) external {
        require(msg.sender == player2);
        play2 = _play;
    }
    
    function _strEmpty(string _str) private pure returns(bool) {
        return bytes(_str).length == 0;
    }
    
    function _validMove(string _play) private returns(bool) {
        bytes32 hash = keccak256(_play);
        
        for(uint i = 0; i < moves.length; i++) {
            if(hash == moves[i]) {
                return true;
            }
        }
        
        return false;
    }
    
}