[nerevarthelame]

I can't wrap my head the enormity of reverse engineering a WoW (or any MMORPG) server. It just seems like there are so many possible types of inputs to the actual server, with so much of the logic happening in Blizzard's black box, that it wouldn't be possible to come up with a decent server emulator. Impressive work.

[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

[bombcar]

Surprisingly large amounts were offloaded to clients especially early on - iirc early pvp was a madhouse because “accurate correct line of sight” and other things you should never trust the client on were only done server side in instances.