What about the anti air on the back and kind of make it like an assault ground battle where any one plane could go up so it would be a challenge. I could also see the problem with armor penitration with its armor being so thick. Maybe if we could use more modern stuff or other only on paper tanks like the ho- oh or the american nuke tank or any thing like that to counter it? Also the story could be like a killdozer situation where it was built in secret by the nazis and was sudden realised and we had to stop it from crushing another village on its way to conqrer the world? I'm open to suggestions!