Mountain Biking game with realistic physics and accurate terrain tessellation. Wii-mote support and generic game-pad support (not for commercial use, so licensing issues may not be an issue). Terrain can be imported from DEM files. Mountain bike where you would actually like to go. Also, a trails editor, to add detail to your favorite places. Share and bike with others online. Obviously, a large wish list. I have done some of this in Diretx9.0, but I do not like the lousy system calls without .net, and MS's lack of proper C++ STL support. So, I am trying to learn Xna and C# simultaneously. Will be a multi-threaded architecture, a backend-server to share content across players, ect... . I am sure too much for one person, but it is a wish list of features.
First hurdle, make/modify a game engine in C#/Xna framework. Already have a simple modified engine from MS examples. Xna appears to be a simplified version of DirectX, with integrated .net support. Also, I can use VS2005, if I make a new C# project in VS2005 and include add the Xna dev studio's files. The biggest difference appears to be Xna dev studio does not have the nice class diagrams, nor the class testing utility. Not a big deal since I develop in C++ and cannot utilize these features anyway :(