Things You'll Need
Instructions
Create any art assets that you will need for your game, including scenes, player character models and enemy model. Assuming that you are working on a two-dimensional game, you can develop all of these images in a number of graphics tools, such as Photoshop, Illustrator and Inkscape. If you need to make three-dimensional assets, the free and open source Blender is a good option.
Download Visual Studio (see Resources) and its XNA plugins; XNA is the game development framework for the Xbox. There is no need to purchase the professional version of Visual Studio, so feel free to download the free "express" version; there is also no need to download the tools for all the CLR (common language runtime) languages, since you can only use C# to develop for the Xbox. Downloading Visual Studio Express for C# and the XNA framework is all you have to do when it comes to gathering development tools.
Launch Visual Studio. You will be prompted to pick the type of application you want to work. You need to select the XNA option for the Xbox. You will then be prompted to name your application and tell Visual Studio where you want it saved; you can save the application wherever you want, even if that is on a remote or web drive. After you have input these values, Visual Studio will generate some code to get your application started.
Code any classes that you may need for your game. Due to the number of different types of games that you could possibly develop, there is no advice that would hold true for every possibility. An example player character class might look something like this: class Player { int health; int power; }. This very basic sample creates a class for player characters that have attributes for health and power. Obviously, you are going to want to write custom classes for your game, but the example is guideline for the code syntax.
Click on the "Run" button or hit F5 to begin compiling your project. The compiler will check for any syntax errors in your project; syntax errors are lines of code that violate C#'s rules. You will have to fix any and all syntax errors before the compiler will successfully compile the entire game.