It's Stalker, OK? Not S.T.A.L.K.E.R. That's far too many full-stops for one name. But if this clunky title doesn't put you off, you can grab the original Stalker, and the follow up, Call of Pripyat, for just £6.24 at Steam!
You're saving 75% with this deal, as opposed to buying each game seperately. Stalker is something of a cult-classic on the PC, averaging an 82 on MetaCritic, with Call of Pripyat close behind with 80. This particular deal expires on August 23rd, when both games will return to their individual prices when bought together, so hurry if you're interested.
Set in the near-future, where the already irradiated Chernobyl suffers a second nuclear catastrophe, resulting in all manner of strange things, from mutants to changes in gravity, Stalker follows one of the eponymous wanderers of the waste, who, in traditional videogame form, is suffering from amnesia. Stalker's search the ruins of Chernobyl for lost treasures, but with our Stalker's mind off someplace else, he's forced to discover how he lost his memory, in the process delving deeper into the mystery that is Chernobyl.
Call of Pripyat is a direct sequel to the original, picking up where events left off. The government ordered troops into the zone, but their fleet of helicopters mysteriously disappeared. Alexander Degtyarev, a Ukrainian Security Service agent, is sent into the zone to find their crash-site and uncover what happened. CoP, like the original, allows Degtyarev to determine the course and conclusion of the story, via events and choices made.