One of the scenarios I'm tempted to have a go at in the near future is on Bob Mackenzie's website. Battle for Zossen is the last of Bob's Great Patriotic War scenarios. The action takes place just after the Soviet forces have overrun the German OKW and OKH command headquarters at Wünsdorf before pressing on to try and capture the bridges over the Notte Kanal at Zossen.
Right next door to Wünsdorf was the Kummersdorf armour testing ground where the Wehrmacht tested captured allied tanks but also where the trials of many new German vehicles took place. It is understood that one of the two Maus prototypes was sent from Kummersdorf to help defend the Wünsdorf command complex but that it never got into action. Bob uses this to justify including a Maus in his Zossen scenario.
I'm keen to give Zossen a try and originally planned to follow Bob's advice: If you don't have a Maus, use a King Tiger. But then I thought, "Sod it - I'm gonna build me a Maus!"
Finally, here's a pic with a T-34/85 to give some idea of the scale of this beast!