Yes, you could do a coop of the campaign with other people. But there were other things you could do. There was a good toolset for the game so some people would make servers. Some were just arena battles with other characters, some were dungeons that you could slash through as a group. Then there were my favorite servers, the roleplay servers. Some people would make a copy of a pen and paper module, that was usually when there was a DM and a group of people who knew each other though. It was like like a game of PnP but online. There were also persistant worlds, basically a free MMO. Some were normal, some were roleplaying. Most of the time I spent playing the online game was on a PW RP server.