using System;

using System.Web;

public class Program

{

    public static void Main()

    {

        var playerName = "https://my.examplegame.com/?charactername=NAME_HERE";

        var uri = new Uri(playerName);

        var queryString = HttpUtility.ParseQueryString(uri.Query);

        Console.WriteLine("Name is: " + queryString["charactername"]);

    }

}