The GOG release is favored by many enthusiasts because it typically includes critical updates and modern compatibility fixes out of the box:

Developers GSC Game World meticulously recreated real locations like Pripyat and the Chernobyl Nuclear Power Plant to provide a hauntingly authentic atmosphere. Go to product viewer dialog for this item.

Released originally in 2007, Shadow of Chernobyl (Czech: Stín Černobylu ) immerses players in an alternate-reality Exclusion Zone following a fictional second disaster in 2006. You play as the "Marked One," an amnesiac survivor tasked with hunting down a mysterious figure named Strelok while navigating radioactive wastes, supernatural anomalies, and mutated horrors. Key Features of the GOG Version

PC Game S.T.A.L.K.E.R.: Shadow of Chornobyl - Enhanced Edition - Shooter Games