GSC Gameworld is trying to do what George Lucas couldn’t – make a prequel that is a compelling answer to questions people have about the elaborate world that they have created. S.T.A.L.K.E.R: Clear Sky takes place one year before the events in the original S.T.A.L.K.E.R and is intended as a gap filler. “There are a lot of white spaces in the S.T.A.L.K.E.R universe,” explains PR manager Valentine Yeltyshev. “Fans and critics had a lot of curiosity about this place.” So, GSC has cast you as a mercenary S.T.A.L.K.E.R, opposed to the hero from the first game, just so you can get a better grip on their alternate post-Chernobyl scenario.

The prequel is big. The largest level, Yeltyshev says, has 6 million polygons – double the size of the largest level in S.T.A.L.K.E.R: Shadow of Chernobyl. It would take over an hour for your character to walk from one side of that map to the other. Part of this size is because the engine is newly optimized, allowing larger and more detailed areas.

Another part is fan service; give people regions they can explore and then reward them for going off the beaten path. The story line itself is less than twenty hours of game, but once you throw in faction wars and the exploration, they hope that the experience of gamers will take much longer than that. Since many fans wanted their S.T.A.L.K.E.R hero to do more artifact collection and less selling of weapons, the economy has been redone to avoid the problem of having more money than you could possibly spend. Artifact collection is now the key to selling for profit, and the money can now be used to upgrade and repair weapons.

The biggest change in the gameplay is in the AI controlled squads. While Yeltyshev talked and demonstrated the size of the world, the AI squads completed the missions they had been assigned with no interference from his character. They make good use of cover and terrain, will not stand still in a firefight and can operate independently (if inefficently) from player control. The AI is not so good that it can play the game without you, but knowing that a squad of drones can clear out a bandit nest without you is a little emasculating.