If anyone is wondering if there's any relation with the S.T.A.L.K.E.R. games, like me:
> While not a direct adaptation, the video game series S.T.A.L.K.E.R. is heavily influenced by Roadside Picnic. The first game in the series, S.T.A.L.K.E.R.: Shadow of Chernobyl, references many important plot points from the book, such as the wish granter and the unknown force blocking the path to the center of the zone. It also contains elements such as anomalies and artifacts that are similar to those described in the book, but that are created by a supernatural ecological disaster, not by alien visitors.
> The book is referenced in the post-apocalyptic video game Metro 2033. A character shuffles through a shelf of books in a ruined library and finds Roadside Picnic, he states that it is "something familiar". Metro 2033 was created by individuals who had worked on S.T.A.L.K.E.R. before founding their own video game development company. The game was based on a novel of the same name which also took influence from Roadside Picnic.
The game is more like the Stalker movie than the book.
In the book there were research missions and active urban life as well as smuggling, whereas the movie is spearheaded on going through the Zone while uninvited. The movie also has the post-apoc vibe whereas the book does not. The whole point of book is co-existence of the unknown with normal(ish) human society.
I don't think S.T.A.L.K.E.R. bears much relation to Roadside Picnic. There are no monsters in the novel (the zombies are "returned people" and are harmless), and the deadly traps are unknowable and nonsentient things more like forces of nature rather than beasts hunting people. Plus there's no radioactivity nor connection to Chernobyl. The plot happens in an unnamed American city, even!
The novel is not a horror novel. It may be considered existential horror, though.
Also, about Metro 2033 (game):