S.T.A.L.K.E.R. Anomaly mod for S.T.A.L.K.E.R.: Call of Pripyat
www.moddb.com
The stand-alone mod S.T.A.L.K.E.R. Anomaly aims to be the most stable and customizable experience for fans of the S.T.A.L.K.E.R. games. It's powered by the Monolith 64-bit engine, a custom fork of the X-Ray engine.

It's stand alone, free, and full as fuck of STALKERy goodness. You can be a bandit! You can be in the Monolith! There's also a thriving mod scene just for it. If you've never run for your life through an anomaly field in the middle of a storm while zombies and Monolith are gunning for you, you've never lived.

It's necessary for human health and life, namely yours. Play it. Vrag Monolita.