The campaign uses in the World of Greyhawk setting as its home world. Year and specific history matters little, as we are mainly using Greyhawk as a setting to move about and develop our own adventures. The party begins in the City Of Greyhawk and will likely use it as a "home base" to return in between adventures.
The game is played with Dungeons & Dragons 3.5 rules with a healthy amount of House Rules added.