This isn't the first book published by the developer, but it is the only one outside of the Angry Birds universe, and it's also one of the company's first big attempts to diversify. Up until now Rovio has seemed content to ride the success of Angry Birds, one of the first blockbuster mobile games — we've seen everything from Transformers -themed spin-offs to a planned animated feature film. But that single-natured focus has hit the company hard, as its growth slowed, forcing a large number of layoffs at its Helsinki headquarters. "As we consider these painful measures, we keep our eye on always delighting our fans with products they love," CEO Mikael Hed said at the time.