Here is a blog post layout covering the significance of that specific early version and why "part2.rar" files are a gamble you don't need to take. Kerbal Space Program 2: The Ghost of Version 0.1.1.0

Why this specific early build defined the KSP2 conversation.

When KSP2 first hit the shelves, it was... heavy. Even high-end NASA-grade PCs were struggling to maintain 30 FPS.