Windows 7 it's easy. Plastik was like that before Windows 7 itself. Just set that theme under Plasma 6 and you are done. Also, QTCurve.

One can argue that Windows 8 is easy as well but here we are (https://github.com/kavinunethsara/tiledscreen)

Sure one can try to patch our way and this is what people suggest but if we are already having windows 8, Please lets just have windows 7 as well, there is no harm in it.

I hope that the author of the project or its community about the win 8 DE could look at resurrecting/creating win 7 DE ootb as well.