I've been thinking for a while now and I'm not sure if D6 is an actual bunker silo or the metro 2 line, if there's a thread about this please tell me, and could anyone explain?
If i rerember D6 and the metro 2 line are sort of the same thing D6 is a underground Spoiler Chemical and biological weapon storage facility With some weapon and food facilitys
I believe Metro-2 does exist and is connected to the Kremlin for getting VIPs to bunkers, but it doesn't officially exist. At least to my zero knowledge.