Fans of the FPS videogame series S.T.A.L.K.E.R., which first came out in 2007, will be gulping down more than their Anti-rads: they also have a bitter pill to swallow. The sequel to the popular GSC Game World video games, S.T.A.L.K.E.R.: Shadow of Chernobyl; S.T.A.L.K.E.R.: Clear Sky (prequel); and S.T.A.L.K.E.R.: Call of Pripyat (sequel) has officially been cancelled.