Hi,
I can help you develop the login pages using the MVC or ASP.NET Web Technologies in C#. Please provide the details of who the users are, the user plans and other details required while login into the system.
Please also provide what exactly you are looking after when you say, you need an interface. Also I would be interested to know how you want to integrate the game code into the website.
Please feel free to ask any questions that you might have.
Regards,
Kunal