PLASTICA-MAN
Member
That's exactly what an iterative engine is. They're not starting from scratch but they're overhauling almost everything.
To make an engine from scratch, you need to build a time machine, go back and invent computers, then an OS for them, then new programs and tools for coding, then a new engine, but you will find yourself copying or using the same architecture and codes you knew in the future you came from. There is nothing built from scratch in this world.