Using the assets from the book
The techniques in this book were not invented by me, so you are completely free to use any/all code from this book in your own games, free or commercial. I also have no problem with you using any of the assets (graphics and sound) in your own games, free or commercial.
The only restriction is that you can't publish the code itself or otherwise make it available, especially in tutorial form, as this would likely bring you into copyright problems with the publisher as well as devaluing the many months I spent putting this work together.
If you have been helped by, inspired by, or have used my assets, I would be grateful for credit, but it is not required.
Important note
I would love to hear from you if you have published a game using the techniques, code, assets, and so on gleaned from this book. But again, this is in no way required.