Actually I'm producing ambient tracks for the S.T.A.L.K.E.R. mod: Lost Alpha ( Moddb.com )
These tracks are inspired by the original S.T.A.L.K.E.R. OSTs and ambient acts like Pete namlook, Tetsu Inoue, etc. So the style will be catch up feelings like "feeling lost", "lonely", "scary", "falling in darkness".
Here you can listen to a little previewmix: Youtube.com