The GSC Game World-developed shooter prequel was previously expected to hit September 5, but suffered a delay due to a North American manufacturing problem that reportedly saw the game head to stores without the CD key codes required for play.

Curiously, a cloud of uncertainty hangs over the game's once-simultaneous release on Valve's digital distribution network Steam.

Though Valve has announced that S.T.A.L.K.E.R.: Clear Sky will be downloadable on September 15, Deep Silver today stated digital download release date "has not yet been determined."