I used to play WOW. One week I wasn't able to play. When I logged back in I found no one else in my guild logged on. This went on for a while (days or weeks, can't remember), nobody around.
Eventually I contacted one of them (they were all people I knew in real life), turns out while I was away they all agreed to move to a roleplay server and swap sides, and forgot to tell me. 😞
I moved over and they offered to power level me to catch up, but that wasn't fun (I did one dungeon with them, they ran ahead and killed the boss before I even got to see it). So I mainly played solo. I lost interest and stopped playing.
Since then, the closest thing to an MMO I've played is Second Life, but I play that differently to most. I teleport to a region, activate the debug camera (which supports my 3D Connexion 6DOF controller) and fly the camera around taking screenshots of the crazy stuff I'd find.
Anyway, what I found more fun was reverse engineering the data formats. I was part of the Asheron's Call 3rd party community. I created the first textured world viewer (others had untextured viewers). I experimented with WOW formats too.
