Before MMOs like Everquest and World of Warcraft, there were MUDs. MUD stands for Multi User Dungeons. Unlike MMOs, MUDs are completely text-based. This means a coder writes a description and you get to use your imagination to paint a picture in your mind. Before MMOs, MUDs would have hundreds of players online at a time and sometimes there would even be a waiting list to get in (not so much these days, but usually there is 100+ players on during the day).
I enjoy the MUDs that I write for, not so much for the game, but more for the community. I have found in MMOs that even though there is a great range of ages, most of them have a high level of immaturity. For the most part, MUDs usually have a couple of annoying people and they get ignored.
I enjoy writing for MUDs because it is a creative outlet for me, though a lot of the time I'll have writer's block which I can overcome if I just start typing.