Rovio's latest venture has nothing to do with Angry Birds. Later this year, the company best known for that game where you fling birds at pigs will launch the first of a new series of pirate-themed novels aimed at young girls. Called Storm Sisters: The Sinking World, the book is penned by Finnish author Mintie Das, and Rovio describes it as "a high action pirate adventure with a female twist."

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.

As for Storm Sisters, Rovio says that the book has already secured publishers in France, Hungary, Indonesia, and Finland, and it is one of 11 finalists selected to appear at the "Books at Berlinale" festival in Germany. "To be a part of Berlinale shows us the exciting potential our new young adult series has both as a novel and a possible film," says Rovio's publishing director Laura Nevanlinna. It's also yet another attempt from Rovio to court young girls, following the launch of Angry Birds Stella.

A second book, called The Frozen Seas, is already in the works and expected to debut soon after The Sinking World.