S.T.A.L.K.E.R. - Lost Alpha is a global modification of the S.T.A.L.K.E.R. The Shadow of Chernobyl". It does not depend on the original game at all. In this game the locations are greatly expanded, most of them were redesigned with GSC, but there are also new territories.
There are a total of 30 locations in the game, 8 of which are underground. The "Kordon" location has not undergone significant modifications.