S.T.A.L.K.E.R.: Clear Sky

S.T.A.L.K.E.R.: Clear Sky was released by the Ukrainian studio GSC Game World in 2008 as a prequel to the successful Shadow of Chernobyl. It is set shortly before the events of the first game, when a mercenary named Scar heads into the Zone around Chernobyl to find out what caused the so-called Emission, which fundamentally changed the balance of power across the whole area. The game develops the world of the Zone with a system of faction wars in which individual groups of stalkers fight over control of territory and its resources, and by taking the side of one faction the player can influence the course of this conflict.

Gameplay is still a combination of first-person shooter and survival horror with RPG elements. The player manages equipment, repairs and upgrades weapons and armour at traders, and has to face human enemies as well as mutants and anomalies scattered around the Zone, which must be avoided or detected with special detectors. The newly introduced weapon upgrade system lets the player gradually tailor their gear to their play style, while reputation with individual factions affects prices at traders and the willingness of other stalkers to help in battle. Clear Sky was built on the same X-Ray engine as the first game, which at release brought a number of technical complaints about optimisation and stability, although visually it was a noticeable step forward thanks to improved lighting, weather effects and denser vegetation.

Despite its technical flaws, Clear Sky has kept a good reputation among series fans for its atmosphere, its faction system and its expansion of the story with the circumstances of the first catastrophe. It is still seen today as an important, if imperfect, instalment that completed the picture of the Zone before GSC closed the series a year later with Call of Pripyat and its more polished mechanics. For many players Clear Sky remains above all the game that best captures the raw, merciless atmosphere of the series' early concepts.