Service Account Google Analytics OAuth AccessType = Offline C#
https://accounts.google.com/o/oauth2/auth?response_type=code&client_id=YOUR_APP_ID.apps.googleusercontent.com&access_type=offline&scope=https://www.googleapis.com/auth/analytics.readonly&redirect_uri=HTTP://YOUR_CALL_BACK_URL
	
curl -d "code=THIS_IS_YOUR_CODE&client_id=YOUR_APP_ID.apps.googleusercontent.com&client_secret=YOUR_APPS_SECRET_CODE&redirect_uri=HTTP://YOUR_CALL_BACK_URL&grant_type=authorization_code" https://accounts.google.com/o/oauth2/token
	
using System;
using DotNetOpenAuth.OAuth2;
using Google.Apis.Authentication.OAuth2;
using AnalyticsService = Google.Apis.Analytics.v3.AnalyticsService;

class Program
    {
        public static void Main()
        {
            var client = new WebServerClient(GoogleAuthenticationServer.Description, "YOUR_APP_ID.apps.googleusercontent.com", "YOUR_APPS_SECRET_CODE");
            var auth = new OAuth2Authenticator<WebServerClient>(client, Authenticate);
            var asv = new AnalyticsService(auth);
            var request = asv.Report.Get("2012-02-20", "2012-01-01", "ga:visitors", "ga:YOUR_GOOGLE_ANALYTICS_ACCOUNT_ID");
            request.Dimensions = "ga:pagePath";
            request.Sort = "-ga:visitors";
            request.MaxResults = 5;
            var report =  request.Fetch();
            Console.ReadLine();
        }

        private static IAuthorizationState Authenticate(WebServerClient client)
        {
            IAuthorizationState state = new AuthorizationState(new string[]{}) { RefreshToken = "REFRESH_TOKEN" };

            client.RefreshToken(state);
            return state;
        }
    }