Behind the scenes of emulating online games

[Brisco]

I'm just trying to understand the workings that go on with emulating online games like Everquest, Ultima Online and Ragnarok Online.....

So, basically it's just a lot of packet sniffing and in game research that goes into emulating (hence the word) games, and then trying to put all that data collected into your own original programming code that works similar to the real game? What about things like enemy AI, is that created from scratch?

You don't have any access to the server binaries or source code do you?