It is not known what it was like before the end of Z-Omega. However, it is known that after Z-Omega, the Death Doctor, Shadow, Kaetie, and Kaetie's Friends were transported to this universe. Everything else is not currently decided yet.
It is not currently decided, as with the history, but it is known that will be apocalyptic, with the color grey everywhere, and the sky always being grey, with fog in the distance. There will be a couple of survivors, and yet some non-survivors, who will be referred to as the Absentians from now on. See more on Gray.