And then suddenly Pz.IC-tan
I remember seeing the German plans about this. The Waffen SS planned to use this in combat, having been birthed from one of their own experiments in the underground labs of Owl Mountains, Occupied Poland. However, because of the Soviet push on the German army in the later times of the war, Pz.IC-tan ended up having to be transported secretively into the deeper homeland of Germany. At this time, her build was mostly produced, and tests had shown that even during combat and in full-sprint mode, the roads were not as damaged as the Ratte would have.
During more testing, it was shown that there were large struggles for her to get over bridges. Although this could be done by herself for stepping over things like ravines or cbrown towns, she required a lot of support to be transported over large bodies of water. This caused troops to have to focus on two large objectives, one of which could be extremely fatal for them. Because of this, it was planned that she was transported further deep into German territory as the Russian advance continued.
Near completion of her production, German scientists had managed to sketch Pz.IC-tan out, showing in full detail what she would be like. Soon, a detached Pzkpfw II turret was to be placed for a primary-like weapon, but it was also planned out (in writing) that it would be swapped out with a Pz. IV 75mm turret. Crews were to maintain her through the chest armor (as shown in this 3D model), but not too long after they've been placed in and she was functioning, they reported that there was "near unbearable amounts of heat.", according to them. This caused a drawback in both research and production.
It's at about this point that the latest known models of Pz.IC-tan were made. Having now been pushed back as far as possible, Pz.IC-tan was forced to be transported between both underground and above ground facilities. Her body and armor were now near-completely made, and her primary Pz. II detached-turret primary was now made, but without the handle or trigger. Her helmet was also made, but in a very early state that it appeared to be temporary. This was also at a time in which she could barely function, but was a basic human-armor mix at this time. Production and research had to be stalled for a long moments time due to the high amounts of armor and infantry being taken in by the Wehrmacht at the time.
Documented by a scientist working on this project, the last document about Pz.IC-tan was written on January 10th, 1945. During surface work on Pz.IC-tan, crews had to be evacuated due to distant air raid alarms sounding. Risking their own lives if they were to take Pz.IC-tan, they were forced to leave their work behind and flee to the Berlin region. Heavy bombardment rained down onto the factory, ruining what model there was of Pz.IC-tan. The detached turret, however, survived and was scrapped by a German search party, being used for ground defense on the outskirts of Berlin.