S. T. A. L. K. E. R. : Shadow of Chernobyl is a first-person shooter with role-playing and survival elements, and the first game in the S. T. A. L. K. E. R. series. It is set in an open, hazardous area known as the Zone, based on the Chernobyl exclusion zone, where players explore wilderness, settlements, and military sites in search of valuable artifacts. Beyond combat against human factions and mutated creatures, players must contend with pockets of altered physics called anomalies, radiation, hunger, and bleeding, managing supplies and equipment to survive. A non-linear storyline offers multiple endings, and limited trading and dialogue with other characters shape the experience.

In an alternate history, a second mysterious disaster strikes the area around the Chernobyl Nuclear Power Plant years after the original 1986 accident, leaving behind a lethal territory called the Zone that is populated by mutated creatures, deadly anomalies, and scavengers known as stalkers. The player takes the role of the Marked One, a man who survives a crash with no memory of his past. His only clues are a tattoo reading S. T. A. L. K. E. R. and a handheld device carrying a single instruction: kill a man named Strelok. Working for a local trader to repay a debt, the Marked One follows this trail deeper into the Zone, gradually uncovering hints about Strelok and the secrets hidden at its heart.