S.T.A.L.K.E.R.: Shadow of Chernobyl is on sale for a measly $5 from now until November 2 on Steam. If you know the importance of this scenario, chances are you already own the game.
If not, well, you have little to no excuse not to. The game may be far from perfect, but what it lacks has been made up for by its devoted fanbase of modding extraordinaires. Now would be the opportune time to see what all the fuss is about before the stand-alone Call of Pripyat expansion is out here in the States.
And while we're on the topic of cheap PC games that are worthy of your time, The Witcher: Enhanced Edition Director's Cut is 50% off -- that's $19.99 -- until the 29th of this month.