S.T.A.L.K.E.R. - PreSky is a Total Conversion mod for Clear Sky, set before the events in Clear Sky begin. Its goal is to provide a fresh new game experience from the point of a regular Stalker within the Zone. This basically means that the mod has complete and total freeplay from the start. PreSky combines some of the best elements and ideas from all 3 games in the S.T.A.L.K.E.R. series to produce a brand new gameplay experience within the Zone, with the sole intention of creating a more realistic Stalker experience that aims to make the player believe they are a Stalker. There is no main storyline progression to unlock new areas, or new items for the player. The Zone goes on living regardless of the actions of the player, with a virtually unrestricted alife that makes the Zone seem even more alive and real than it did before. The only storyline is the one you create for yourself.