With S.T.A.L.K.E.R: Shadow Of Chernobyl we wanted to establish a 'what if' scenario based on the very real and very terrible events of 1986 when Reactor Four at Chernobyl blew. Our storyline posits a second explosion in 2006 that essentially creates what we call The Exclusion Zone around the reactor site. It's this Zone that defines the scope of the game as it contains the perversion of nature as effected by the release of such a high dose of radiation. Here we can create an area that allows the range of incidents and opportunities we need for a game of such ambition. Here we can set up our own laws, both natural and unnatural, in which the 'real' world can interact in a way that feels acceptable for gamers.

The mutative signs of the radiation can be seen and felt in ways that maintain a cohesive reality. In the Zone this radiation has effected massive changes to the environment. The region becomes a place where mutants come in many different forms and with many different abilities. As varied as nature itself, these side effects of the second explosion roam the area, turning it into a lawless, uncontrollable land that is twisted for individual need and greed. The creatures here are possessed of more than natural cunning. These hyper intelligent abnormalities are more than a match for anyone, however well armed, who enters the Zone looking for personal gain. And so few even think of making such an attempt. Scientific and military expeditions quickly cease their forages and the tendency to disappear produces too high a cost. Sealing off the area and politically defining the Zone, the Government's position appears to be one of containment. And whilst it appears to be working in terms of preventing the horrors from escaping, it overlooks the need to keep other horrors from entering.

A new breed of mercenary is seen in the game. These are the S.t.a.l.k.e.r.s, a band of people linked by activity rather than formal affiliation. The stalker will risk his or her life in the Zone on a daily basis, looking for that lucrative job - whether it is retrieving an artefact for some rich collector, scouting for intelligence or even rescuing some other, hapless and would-be s.t.a.l.k.e.r. The s.t.a.l.k.e.r, just like the Zone they roam within, knows few boundaries and is as open to change as the mutations within.

It's with these people that the game really starts six years after the second explosion. The Zone is a fully formed region, talked about in the media and home to all manner of abnormalities. S.t.a.l.k.e.r.s come and go regularly and the most experienced develop an affinity with the subtleties of the phenomenon. Knowledge is their first weapon and their first objective. Beyond this we have choice.

S.T.A.L.K.E.R: Shadow Of Chernobyl takes this choice as the bedrock of the game structure. Always aware of the presence of death - often in cruel and unusual disguises, a s.t.a.l.k.e.r will learn as much as possible about the environment. And there is a lot to learn. The Zone is constantly evolving, mutating into new forms as creatures of every size and shape shift about the land in response to built in urges or as a reaction to new dangers. This highly complex play of cause and effect makes for a difficult playing terrain and a randomness that prohibits complacency. Even anomalies become as much a part of the landscape as the sunrise (only far less predictable in their occurrence). Hunger, fatigue and the constant effects of radiation on the body play a key part for everyone within the Zone - notably the player's stalker who must take their own health and their own needs into consideration with every step they take.

It's this vastly evolved life simulation system that sets S.T.A.L.K.E.R: Shadow Of Chernobyl apart from other experiences. It sets new standards for the MMORPG approach to gaming and ups the stakes in action adventures. Objectives and missions become subject to the whims of individual choice as players integrate themselves in the S.T.A.L.K.E.R world. Non-player characters have their own priorities, some of which may or may not clash with those of the player. Their abilities grow as they become increasingly familiar with the landscape and the altered laws that govern it. How you react becomes as much a part in developing a sense of character as surely as finding new weapons or artefacts. Again we place huge emphasis on cause and effect within scenarios; the shoot now ask questions later approach will yield a vastly different outcome than that of invisible infiltration.

Hundreds of possibilities are open to a s.t.a.l.k.e.r within the Zone and not every danger will present itself in physical form. The beauty and achievement of the game's parameters is to establish a hyper realistic world that at once seems eerily familiar and dangerously alien. Should a player work to uncover the secrets of the Zone, and of the phenomena within then they can face over eight different endings offering a vastly rewarding game-play experience.