Wasn't the Aether locked-off Earth after Tag? How could 115 have made their return? What exactly is the enormous device we see in the trailer? The map is also set at a meteorite impact, which hints at 115.

Speaking of which, we saw Juggernog, a Raygun and a monkeybomb in the trailers, which would mean that Group 935 had existed in this universe. That latter has a huge network of tunnels beneath, filled with ancient artifact, which may hint at some Keeper stuff? How could this relate to the maschine in the Polish map which seems to tap into the Dark Aether? Now there's a location in red on that map this could be the city of Hái Phòng, or more specifically Hạ Long Bay. Would this mean this map takes place prior to 'Die Maschine' and the Cold War campaign? The interesting thing about this is the photo of the choppers, which definately relates the the Vietnam war, which took till 1975. I'm not fully sure whether these are spoilers or not, but word it says that next to 'Die Maschine', there will be a second zombies map this time set in Vietnam.

Die maschine map