Ambitious. Could have been special. Potentially great concept and gamplay hindered by poor optimization and system needs
Gameplay: The gameplay for this game is rather ambitious, and isn't bad at all once you get used to it. In fact, it works out quite well. Firefights can be unpredictable at times and the AI, although not amazing does have its ups. In addition to this, the concept, despite it not being the most refreshing does allow the game to play out well. There isn't too much to say about S.T.A.L.K.E.R.'s gameplay though because it is mostly generic at times like many of todays other FPS's. One element that does make this game as an FPS stand out from the rest are its RPG elements. The ability to manage your inventory, carefully choose your weaponry and keep an eye on its condition do add an extra appeal.
Graphics: Generally speaking S.T.A.L.K.E.R.'s graphics aren't anything special, and aren't much better than that of HL2, if not on par. That being said, the system requirements for S.T.A.L.K.E.R. are ridiculously high, compared to games such as HL2 (inc. Ep1) and CoD2 which both have very good visuals and require much less resources. In addition to that, S.T.A.L.K.E.R.'s optimization is terrible and even on a high end system results in lag issues.
Sound: The sound effects in S.T.A.L.K.E.R. are actually quite good, despite the lack of visual aid to match. Sounds from treading gently on grass, to running on concrete and the hammer of each round fired, add to the murky presence and intensity of the game.
Conclusion: It must be noted that despite S.T.A.L.K.E.R.'s high system requirements and disputable graphics, what the game lacks in is certainly made up for in gameplay. The game is relatively short but does have replay value, if only for 1 or 2 times after initial completion. However, it is advised that some of the mods created for it (i.e. ones that improve FPS) should be used as it certainly does enhance gameplay. Certain bugs and other issues are mostly fixed in the patch releases as well, so be sure to pick them up and install them before playing.