After getting interested in new FirefoxOS out of curiosity I looked into the development of this new mobile platform from mozilla, incidentally leanpub has couple of free books on the subject, I downloaded it on my iPad and thought about reading it whenever I got some free time, on a free weekend I thought I should at least start with it.
I took my iPad and went for a walk thinking about reading it on the way, the book is Building Games for Firefox OS by Andre Garzia, I would say the book is not for beginner but even if you have made a simple enough or understand the different paradigm of simple app development then it is easy enough to follow. with mere 136 pages you can't beat the price. It's also free to read online here.
The book is divided into several small sections which is pretty easy to follow, it is very opinionated without coming out as with forceful advice, the author used phaser gaming framework which seems like a nice choice for starters, in the course of 13 small chapters we build a breakout like game and each chapter won't take more than 15 minutes to finish(in most cases it would take less than 10 minutes), the content is divided into digestible small chunks and you would be finished with a fairly playable breakout like game with basic levels system and a nice introduction to different gaming concept, I really enjoyed the book and would definitely recommend it, author did a good job in presenting information and even provided the complete code.
The game created is foxnoid, take a look at the screen-shot.