S.T.A.L.K.E.R. Anomaly is a standalone mod for the FPS RPG game S.T.A.L.K.E.R.: Call of Pripyat. You don't need to install it on other stalker games, just download the package, unpack it on an empty folder and play. The game is powered by the Monolith 64-bit engine, a custom fork of the X-Ray engine. It is currently ranked the most popular mod on moddb.
https://www.moddb.com/mods/stalker-anomaly
https://www.youtube.com/watch?v=lTrlsXKAe1E
