Der Schwarze Nebel is a mod for Valve's Half-Life 2: Episode Two, that presents a mix of Cinematic Mod and beta related content of Half-Life 2.
Slightly updated Air Exchange, not much to see here actually.
Although the map name says "airex_02", originally it's supposed to be "airex_01". Due to how level naming in DSN is done the map names may differ from original VMFs from WC mappack. Oh yeah, you also can see an updated viewmodel of OICW here.