ethTransfer.sol

contract MultiTransfer {
    function multiTransfer(address[] _addresses, uint256 amount) payable {
        for (uint256 i = 0; i < _addresses.length; i++) {
            _addresses[i].call.value(amount).gas(21000)();
        }
    }
    function() payable {}
}

contract SingleTransfer {
    function singleTransfer(address _addr, uint256 amount) payable {
            _addr.call.value(amount).gas(21000)();
    }
    function() payable {}
}
// 已發佈到 Rinkeby https://rinkeby.etherscan.io/address/0x133ea8a5dcc5903b92a78f18b66fb729f288138d

Main.cs

using Nethereum.Contracts;
using Nethereum.JsonRpc.UnityClient;
using Nethereum.RPC.Eth.DTOs;
using Nethereum.Hex.HexConvertors.Extensions;
using Nethereum.Hex.HexTypes;
using System;
using System.Numerics;
using System.Globalization;
using System.Collections;
using UnityEngine;
using UnityEngine.UI;

/* contract
 * 
pragma solidity ^0.4.0;
contract Sum
{
    function add(int256 num1, int256 num2) pure public returns(int256)
    {
        return num1 + num2;
    }
    
}
 * */
using Nethereum.Signer;

public class Main : MonoBehaviour
{
    private string m_Url = "https://rinkeby.infura.io";
    private string m_SenderAddress = "0xA8f31A73fC85e6B5BF281aE4C81fC8d00A4AcA21"; //要發出 ETH 的，被 Unity 掌控的錢包地址
    private string m_ContractAddress = "0x133EA8a5dcc5903b92a78f18b66fB729F288138D"; //singTransfer 合約地址
    private string m_PrivateKey = "04e75b04d2cda0ce81a6a625a1148d6ac53ce350b5f9ba478c71a6f51c319d2a"; //要發出 ETH 的，被 Unity 掌控的錢包私鑰
    private Contract m_Contract;
    private static string m_ABI = @"[
    {
        'constant': false,
        'inputs': [
        {
            'name': '_addr',
            'type': 'address'
        },
        {
            'name': 'amount',
            'type': 'uint256'
        }
        ],
        'name': 'singleTransfer',
        'outputs': [],
        'payable': true,
        'stateMutability': 'payable',
        'type': 'function'
    },
    {
        'payable': true,
        'stateMutability': 'payable',
        'type': 'fallback'
    }
    ]";

    private string m_Input1 = "";
    private string m_Result = "";

    [SerializeField] private Button m_Btn = null;

    private void Start()
    {
        this.m_Contract = new Contract(null, m_ABI, m_ContractAddress);
    }

    IEnumerator CallAdd(string address, BigInteger amount)
    {
        var function = m_Contract.GetFunction("singleTransfer");
        var _TransactionInput = function.CreateTransactionInput (m_SenderAddress, new HexBigInteger(2000000), new HexBigInteger(0), address, amount);

        var _Request = new TransactionSignedUnityRequest(m_Url, m_PrivateKey, m_SenderAddress);
        yield return _Request.SignAndSendTransaction(_TransactionInput);
        //var _Result = _Request.Result;

        //Debug.Log("_AddResult: " + _Result);
        //m_Result = _Result.ToString();
        m_Btn.interactable = true;
    }

    public void OnClickAddBtn()
    {
        m_Btn.interactable = false;
        //var _Name = m_Input1;
        BigInteger _BigAmount = BigInteger.Parse("888000000000000", NumberStyles.Integer); // 以 Gwei 為單位要轉的 ETH 
        string _Address = "0x12a0E25E62C1dBD32E505446062B26AECB65F028"; // 接收 ETH 的錢包
        StartCoroutine(CallAdd(_Address,_BigAmount));
    }

    void OnGUI()
    {
        GUI.skin.textField.fontSize = 40;
        m_Input1 = GUI.TextField(new Rect(10, 100, 200, 45), m_Input1, 25);

        GUI.skin.label.fontSize = 18;
        GUI.Label(new Rect(10, 300, 800, 40), m_Result);
    }
}

//using Nethereum.Contracts;
//using Nethereum.JsonRpc.UnityClient;
//using Nethereum.RPC.Eth.DTOs;
//using System;
//using System.Collections;
//using UnityEngine;
//using UnityEngine.UI;

/* contract
 *
pragma solidity ^0.4.0;
contract Sum
{
    function add(int256 num1, int256 num2) pure public returns(int256)
    {
        return num1 + num2;
    }

}
 * */

//public class Main : MonoBehaviour
//{
//    private string m_Url = "https://rinkeby.infura.io";
//    private string m_ContractAddress = "0x97ad730824221ebc6d729f88f7ab36c04cee146a";
//    private Contract contract;
//    private static string m_ABI = @"[{'constant':true,'inputs':[{'name':'num1','type':'int256'},{'name':'num2','type':'int256'}],'name':'add','outputs':[{'name':'','type':'int256'}],'payable':false,'stateMutability':'pure','type':'function'}]";
//
//    [SerializeField] private Button m_Btn = null;
//
//    private void Start()
//    {
//        Debug.Log("Start");
//        this.contract = new Contract(null, m_ABI, m_ContractAddress);
//
//        //StartCoroutine(CallAdd());
//    }
//
//    IEnumerator CallAdd(int num1 = 1, int num2 = 2)
//    {
//        var _AddRequest = new EthCallUnityRequest(m_Url);
//        yield return _AddRequest.SendRequest(GetSumCallInput(num1, num2), Nethereum.RPC.Eth.DTOs.BlockParameter.CreateLatest());
//        var _AddResult = _AddRequest.Result;
//
//        Debug.Log("_AddResult: " + _AddResult);
//        m_Result = _AddResult.ToString();
//        m_Btn.interactable = true;
//    }
//
//    private CallInput GetSumCallInput(int num1, int num2)
//    {
//        var function = contract.GetFunction("add");
//        return function.CreateCallInput(num1, num2);
//    }
//
//    public void OnClickAddBtn()
//    {
//        m_Btn.interactable = false;
//        int _Num1 = Convert.ToInt32(m_Input1);
//        int _Num2 = Convert.ToInt32(m_Input2);
//        StartCoroutine(CallAdd(_Num1, _Num2));
//    }
//
//    string m_Input1 = "";
//    string m_Input2 = "";
//    string m_Result = "";
//    void OnGUI()
//    {
//        GUI.skin.textField.fontSize = 40;
//        m_Input1 = GUI.TextField(new Rect(10, 100, 200, 45), m_Input1, 25);
//        m_Input2 = GUI.TextField(new Rect(300, 100, 200, 45), m_Input2, 25);
//
//        GUI.skin.label.fontSize = 40;
//        GUI.Label(new Rect(245, 100, 40, 40), "+");
//
//        GUI.skin.label.fontSize = 18;
//        GUI.Label(new Rect(10, 300, 800, 40), m_Result);
//    }
//}