If you are looking for something that fits the harsh and depressing survival mood of Fallout1&2/S.T.A.L.K.E.R-style post-apocalyptic games, then maybe some of the works of the dark ambient artist Lustmord might suit your needs
The soundtracks of Half Life 2 and portal have some pretty great songs too
(this is where Portal 2 failed, the athmospehre)
But since you said explosions and gangs everywhere, you might as well try some gangsta rap like NWA and go blow some shit up in Fallout3/NV?
