Head Up Display (HUD) or Graphic User Interface (GUI) is the core part of games. Players can navigate the different game screens using the menu, click the button to trigger game events, or use the textbox to type messages to other players. In StarCraft 2, you can click a building symbol to create a unit. In Diablo 2, you can change your equipment by selecting the staffs in the bag list panel. A powerful and rich GUI system will make your game more affable and fascinating.
Actually, Windows Phone 7 XNA framework does not support a built-in GUI system such as Silverlight. This means you should implement your own. Fortunately, if you do not hope to do the radical work while focusing on the game logic and the rendering technique, some third-party GUI packages using XNA, such as Neoforce Controls ( http://neoforce.codeplex.com/) or Nuclex.UserInterface ( http://nuclexframework.codeplex.com/) will do you a favor. Both the third-party XNA GUI libraries are free, and it is convenient...