: You must have every single part (part1 through whichever is the final number) in the same folder .

: You only ever interact with part1.rar . By right-clicking the first part and selecting "Extract Here" using software like WinRAR or 7-Zip, the program automatically pulls the necessary data from part 4 and all other segments.

The "part4" file is a single piece of this larger puzzle. On its own, it is useless; it contains a fragment of the game's compressed data that cannot be read until it is reunited with its siblings. How to Handle Part 4