In the midst of the big EA Steam announcement today, Valve has also revealed what game will get their standard Steam weekend sales deal this week. The lucky game to get the treatement is S.T.A.L.K.E.R. Shadow of Chernobyl, the first game in the first person shooter series from developer GSC GameWorld.

The title, first released in 2007 by publisher THQ, is now on sale via Steam this weekend only for just $4.99 compared to its normal price of $19.99. If you download and enjoy playing the original, you can download and play the sequel. S.T.A.L.K.E.R. Clear Sky was released last September and is also available via Steam.