Burrito actually gave a pretty good description in Chibi's chat. But since I didn't save that, I'll just give a small summary of his summary.
Basically, the whole thing started when Supermeme, an underage b& and the main target of everybody's flames, created a second account, Supersonic, and actually argued with himself. He was banned and Mo and I began making talk about how it would be interesting if the forums was forced to fight against Supermeme in a war-type scenario.
The idea extended to Supermeme leading an army of Lurkers, which were the main population of the original forums at the time. We had about two hundred or so Regulars and people who had a dozen or so posts, while Lurkers who only posted once or not at all were numbering in the thousands(?). Thus we made the idea of Supermeme leading this innumerable army against a small band of Regulars.
In the original forums, we had a chatroom similar to Chibi's chatroom. When Mo and I explained the idea to everyone, it was pretty well taken and we started taking everybody's requests on how their characters should be, the weapons they would use, their appearance, and anything they wanted. It was like an RP that was turned into a story.
Later on as we wrote, we concluded that not only would this be a story about the fictional battle between Lurkers and Regulars, we would use Lurker Wars as a way to chronicle the events of all of us. This means the entire series will actually span from the original forum, to Tentacle Haven, to now. Some key events in the forum history would be a retelling of what happened to the original forums, the adbots from Tentacle Haven, and Linemarvel's return (But that event is waaaay ahead of schedule).
We began the story with frequent updates, but as time passed we eventually got lazy as hell and eventually it led to this. Sinful is now the new author is most likely going to portray the story in a way that we couldn't.