Google Play Games plugin for Unity:

Setting Up Google Play Games Services:

準備
確保你的Android SDK中包含以下內容：
•Google Play Services
•Android Support Library
•Local Maven repository for Support Libraries (Also known as Android Support Repository)
•Google Repository
•Android 6.0 (API 23) (this does not affect the min SDK version).

使用Android SDK Manager 來確認你的SDK內容

如果下載過慢，可以嘗試使用以下站點：

匯入SDK
1.將GooglePlayGamesPlugin-0.9.42.unitypackage檔案匯入到你的專案中
匯入專案後請務必至少修改一次包名(Package Name)，確保你已看到此介面：

*如果已經是正式包名，則新增任意字元，Resolving 結束後再改回正式包名，
  正式包名必須與你在後臺填寫的包名一致。

*如果Resolving結束後彈出以下提示，請選擇NO

*確保Resolving結束後Plugins > Android目錄下存在此檔案 gpgs-plugin-support-0.9.42

2.匯入後選單欄將出現SDK選項，選擇Window > Google Play Games > Setup > Android Setup
面板中 

directory to save constants以及Constants class name使用預設值即可
Resources Definition 在後臺中：

 你還需要從後臺生成Client ID 並填入。

使用

這裡我們只使用到了排行榜功能：

1.AndroidManifest檔案中需加入以下程式碼

<meta-data android:name="com.google.android.gms.version" android:value="@integer/google_play_services_version" />
 

2.實現登入以及排行榜的方法，包括登入、登出、上傳分數以及顯示排行榜:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

using GooglePlayGames;
using UnityEngine.SocialPlatforms;

/// <summary>
/// Google play manager.
/// create by liufeng on 18-01-11
/// </summary>
public static class GooglePlayManager {

    public delegate void GPDelegate(bool success,string uname);

    static GPDelegate authenticatingCallback = null;

	/// <summary>
    /// 初始化SDK
    /// </summary>
	public static void Init () {
        PlayGamesPlatform.Activate();
	}

    /// <summary>
    /// 是否登入
    /// </summary>
    /// <returns>The authenticated.</returns>
    public static bool Authenticated(){
        return Social.localUser.authenticated;
    }
	
    /// <summary>
    /// 登入
    /// </summary>
    /// <returns>The authenticating.</returns>
    /// <param name="cb">回撥</param>
    public static void Authenticating(GPDelegate cb = null){
        authenticatingCallback = cb;
        Social.localUser.Authenticate((bool success) =>
        {
            if (success)
            {
                Debug.Log("Authentication success : " + Social.localUser.userName);
            }
            else
            {
                Debug.Log("Authentication failed");
            }
            if (cb != null) cb(success, Social.localUser.userName);
        });
    }

    /// <summary>
    /// 登出
    /// </summary>
    public static void SignOut(){
        ((PlayGamesPlatform)Social.Active).SignOut();
    }


    /// <summary>
    /// 上傳分數
    /// </summary>
    /// <param name="scores">分數.</param>
    /// <param name="lbid">排行榜id.</param>
    public static void PostScore(int scores,string lbid){
        if(!Authenticated()){
            Debug.Log("沒有登入");
            return;
        }

        Social.ReportScore(scores,lbid,  (bool success) => {
            // handle success or failure
            Debug.Log("post score : " + success);
        });

    }

    /// <summary>
    /// 顯示排行榜
    /// </summary>
    /// <param name="lbid">排行榜id，傳空字串則顯示全部排行榜</param>
    public static void ShowLeaderboard(string lbid = ""){
        if (!Authenticated())
        {
            Debug.Log("沒有登入");
            return;
        }
        if(lbid == ""){
            Social.ShowLeaderboardUI(); 
        }else{
            PlayGamesPlatform.Instance.ShowLeaderboardUI(lbid);
        }

    }
}

GooglePlayTest為測試方法，將此類放到任意場景中，可快速測試SDK的各項功能是否正確

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GooglePlayTest : MonoBehaviour {

    const int height = 70;
    const int width = 200;

	// Use this for initialization
	void Start () {
        GooglePlayManager.Init();
	}
	
    int high;
    void OnGUI()
    {
        high = 10;

        if (CreateBtn("登入"))
        {
            GooglePlayManager.Authenticating(AuthenticatingCallBack);
        }

        if (CreateBtn("登出"))
        {
            GooglePlayManager.SignOut();
        }

        if (CreateBtn("上傳分數"))
        {
            GooglePlayManager.PostScore(123,"CgkImoOim_EUEAIQAQ");
        }

        if (CreateBtn("顯示排行榜"))
        {
            GooglePlayManager.ShowLeaderboard("CgkImoOim_EUEAIQAQ");
        }
    }


    public bool CreateBtn(string btnname)
    {
        bool b = GUI.Button(new Rect(Screen.width / 2 - width / 2, high, width, height), btnname);
        high += height + 5;
        return b;
    }

    public void AuthenticatingCallBack(bool success, string uname)
    {
        if(success){
            NGUIDebug.Log("Authenticating success : " + uname);
            Debug.Log("Authenticating success : " + uname);
        }else{
            NGUIDebug.Log("Authenticating failed  " );
            Debug.Log("Authenticating failed  " );
        }

    }

}

這裡可以在應用商店中搜索"google框架安裝器"，大部分商店中都有，安裝後就可以使用google play服務了。