My first book, on XNA, released a while back, and available for free. Had 2K downloads in the first week. It was a lot of fun. I was particularly proud of the explosion system. It looked at the impact point for the collision, then fractured the image into multiple smaller chunks with random jaggedness, and fiery edges. The book was very much an early work, but included lots of coverage including learning C# in the first place, learning XNA, developing this game, managing an indie team, keeping people motivated, and even marketing. Everything you need to build and release a game.