Ah I thought it was your design. Yes I imagine previous tanks had sloped armour, the Pz.VIII makes much better use of it though than any OTL WWII German tank.Thanks, I found this little gem in Deviantart made by KHK-Wabrik
here is his link: https://www.deviantart.com/khk-wabrik
I don't know how hard it is to make this given I wasn't the one who draw it, But I guess it take a lot of time,effort and skill to create this work of art.
As for the sloped armor, I mean the Pz-VIII already has sloped armor featured armor featured in the design, would the design of it successors also implement the same features?