Initializing Games Client in Android

I had the same problem initially. What I had to do was look at the full, unfiltered LogCat log. There, I saw the message:

GamesIntentService(17929): Using Google Play games services requires a metadata tag with the name “com.google.android.gms.games.APP_ID” in the application tag of your manifest

So, assuming you created an entry in your strings.xml called app_id, try adding the following to your AndroidManifest.xml under the <application> tag:

<meta-data android:name="com.google.android.gms.games.APP_ID"
        android:value="@string/app_id" />

You can find your APP_ID in the Games Services tab