[Zetaphor]

As someone who has reverse engineered an online games protocol (Anyland, admittedly much less complex in scope), I can provide a little insight. I started from a known point that would be easy to replicate and observe, and then just built out from there. Once you've got a foothold you can start to build up an understanding of how the various components interact, and with each new discovery you increase gain new insight into other as yet unmapped systems.

This is still incredible work on their part that would require an incredibly deep understanding of the game mechanics in order to reproduce their artifacts by observation