I am a reformed MUD addict... The first mud I ever played was called Core 2696, which I eventually became a coder for. Two years later it shut down and was reopened as Core 2648 and, sadly, it sucked.
During my time coding on Core 2696 I played a different mud on the side called Myths and Legends, and it was a pretty small mud but it had so many features that you couldn't find on other muds, and the game was actually pretty fast-paced compared to most muds where you have to sit around typing for hours to gain a single level. Now I'm aware that muds aren't all about gaining levels, but there's some points where in order to enjoy playing the game, you have to be powerful enough to be able to survive. A lot of muds try to add to the difficulty by making it so you have play for hours and hours, or even days, to gain a single level. It's just tedious... I enjoy playing on a mud where I can steadily gain levels and move up to more difficult areas, so I can feel like I'm actually getting somewhere in the game...
Anyway, when Core 2648 came up I pretty much moved to Myths and Legends full-time, and eventually THAT mud shut down, and I kind of drifted from mud to mud trying to find something that was good.
I found a pretty good ROM based mud called Purple Dragon, that had a built-in ASCII automapper to add kind of a graphical feeling to the game, and I enjoyed it a lot, but just my luck, that mud shut down too.
A few months later I found another mud called JungleMUD, where a lot of players from Purple Dragon migrated to, and then JungleMUD shut down as well. I haven't really seriously played on any muds since then.
Sometimes I log on a few Nightmare-based muds like Merentha and ShadowMUD, but they just don't feel the same as the other muds I used to play, so I can't enjoy them nearly as much. I've tried to create my own mud a couple times, but without a coding staff it's a tedious and seemingly futile effort.
So, I stopped MUDing.