There is a whole book series based on the book Roadside Picnic and the S.T.A.L.K.E.R. movie. So far, they are only available in Russian. The first book is called S.T.A.L.K.E.R. Shadows of Chernobyl (Russian: Teni Chernobylya). It features a couple of stories written by different authors and fans of the game series.
Later, as the game gained more and more fans, the book series became a hugely successful franchise. However, most of the novelization don't follow the game storyline, neither are the books connected to each other.
The success of the series has resulted in a decline in quality as some of the stories became rather stereotype novelizations applying the same clichés.
Before S.T.A.L.K.E.R.: Shadow of Chernobyl was launched in 2007, GSC teamed up with fantasy author Bernd Frenz to produce German books . Frenz said in an interview that he was given one single afternoon with a beta version and a God mode trainer to get acquainted with the game. He produced three books, although totally different from the actual story. Even so, the books were a success and Panini, the publisher, launched several translations from Russian. However, some of the books were not up to the expectations and they also suffered from low linguistic and production quality.
These are the covers of the other books in the series: