Lost Alpha is a new episode of the S.T.A.L.K.E.R. series made by dezowave group for free!
Pretty much a main menu music replacer, using Immortality by Gamardah Fungus, which was actually used in a LADC atmospheric demonstration video before the release of DC back in 2015
Tried the addon in STALKER LADC Extended. It works.
This stuff really rocks!