If you like to use Lua for game scripting, this is a useful library to check out. Xnua is a library that helps integrate Lua scripting into XNA based games. It uses a content pipeline plugin to convert scripts to .NET assemblies, which rely on the Xnua runtime for support. You can load and run the assemblies more or less normally, and hook them into the Lua states provided by the runtime, in order to add the scripting functionality to your game project.