In XNA, responding to user input, updating your app’s state, and drawing content all happen periodically within the game loop. The game loop is the heart of every XNA game, and understanding it is fundamental to XNA development.
Unlike pure XNA games, which use the
Game class for the game loop, hybrid apps rely on the
Microsoft.Xna.Framework.GameTimer, which is unique to the phone.
In a pure XNA game, a
Game class is used instead of an
Application class. XNA games rely on overloading
Game class methods that are specific to the game loop, such as
Draw, whereas hybrid apps (Windows Phone 7.1 apps that combine XNA and Silverlight) and apps that rely on XNA APIs, such as the sound effect ...