Bellevue (WA) - The prequel to the first-person shooter Stalker will be available exclusively as a digital download on Valve's content delivery service Steam.

GSC Games created Stalker: Shadow of Chernobyl, which was released last year. "Stalker" is an acronym that stands for, "Scavengers, Trespassers, Adventurers, Loners, Killers, Explorers and Robbers." The first title put players in the role of an amnesiac trying to regain his memory. In the course of the game, players can explore several open-ended areas.

Stalker: Clear Sky is a prequel to Shadow of Chernobyl, and will only be available for purchase through Steam, eliminating the cost of retail packaging and shipping.

"We chose to deliver the digital version of the game exclusively on Steam because of its proven success not only as the leading global digital distribution platform for games, but because it allows us to directly reach its integrated and active community of gamers," said GSC Game World CEO Sergiy Grygorovych.