The metagame vision for this setting is to provide a secluded environment with a closed economy. Game play is modeled after the video game in that the stalkers are independent players within the zone, building contacts, exploring the ruins, trading and improving their gear, surviving the horrors of the zone, and ultimately discovering its secrets. It's difficult to imagine that this would be a long-running campaign since ultimately the center of the zone will be reached. This is not a game of epic roleplaying, although drawing upon elements from the book you could certainly take it to a whole intersteller/stranger in a strange land direction. This setting is about grit, survival, and modern horror.
Shadow of Chernobyl & Call of Pripyat video games, but also includes references and ideas from Roadside Picinic and the film Stalker by Andrei Tarkovsky. This is a campaign setting is strongly influenced by three primary sources. It is most heavily influenced by the S.T.A.L.K.E.R.:
The materials for this setting are provided in the Hero System. However, other than specific game mechanics for weapons and such, they can probably be used for other games, or at least as a starting point. All you should really need to play is a copy of the Basic rules (also in PDF for $10), although to really expand on the experience I recommend Post Apocalyptic Hero, the main rulebook, and possibly the Bestiary. The equipment is all provided in HeroDesigner format for quick character making, as well as PDF for printing.