the Maus and panther 2 were not even out of the development stage, the kugelblitz may or may not have been used, the black prince was actually functional
There was a complete Maus tank... even before the Black Prince. The 2nd Maus wasn't fit with the turret... the first one was.
"In March 1944 the second prototype, the V2, was delivered. It differed in many details from the V1 prototype. In mid-1944, the V2 prototype was fitted with a powerplant and the first produced Maus turret. This turret was fitted with a 128 mm KwK 44 L/55 gun, a coaxial 75 mm KwK 44 L/36.5 gun and a coaxial 7.92 mm MG 34. The V1 prototype was supposed to be fitted with the second produced turret, but this never happened."
https://en.wikipedia.org/wiki/Panzer_VIII_Maus
So either we delete the BP or fully embrace the bullshit. if we don't care about which units were deployed, there is no reason the Maus shouldn't be ingame.