Call of Chernobyl is a free-play sandbox mod for S.T.A.L.K.E.R. : Call of Pripyat created by TeamEPIC. It features 32 explorable maps, reworked level design and level fixes, new original level, Trucks Cemetery, Full AI and A-Life overhaul, engine and script enhancements, Repeatable task system which bases itself on A-Life events, Customizable weather environments for every map as well as surges and psi-storms from AF3, Character creation which includes name, portrait and faction selection; Several optional modes such as Ironman mode, story mode and zombie survival mode, New achievements, rankings and reputation system, PDA leaderboard and enhanced PDA statistics, Companion system with keyboard issued commands, many optional side-features and community-made addons . Call of Chernobyl was player's choice Mod of the Year 9th place in 2015 and 1st place in 2016!
Instructions: 1- Make sure that you have OpenAL installed (link below). 2- Unzip the four .dlls (wrap_oal, xrSound, OpenAL32 and soft_oal) to the "bin" folder of Call of Chernobyl mod (make a backup first). Start up the game and there should be a new sound device showing up in the sound settings menu, called "DirectSound". 3- Select that, enable EAX and restart the game. Enjoy surround sound.
If necessary, download OpenAL, that renders 3D sound and is compatible with S.T.A.L.K.E.R., from here - Openal.org .