"Invent Your Own Computer Games with Python" is a Creative Commons-licensed book that teaches programming to complete beginners by making games, available in full at http://inventwithpython.com

Each chapter presents the source code for several simple games, and then explains them line by line. Programming concepts are introduced when they appear in the code, so you always see a practical application to what you are learning and get an idea of what a program "looks like". The later chapters cover the Pygame library to make games with graphics, sound, and animation.

"Invent with Python" takes its inspiration from the days of magazine listings of BASIC source code. Most programming books are expensive, and designed for software developers or other professionals. "Invent with Python" is free to download, written in simple language that is accessible to kids, adults, and international readers. Programming concepts are never introduced outside of the context of their use in an actual program (all of which are under 400 lines.)

Other books and "game creation kits" aimed for children are too simplistic, or are so heavily abstracted behind drag-and-drop GUIs that the actual concepts of real-world programming are lost. Python's gentle learning curve makes it an ideal first language to learn, but still scales up for professional use. This is why I chose Python for a young adult programming book.