I don't know how many people play muds here, basically they're text based online games. They're alot of fun, and will run even on old computers, without a new graphics card, and best of all, they're free.
The one I prefer is called Crimson Nightmares (
http://crimsonnightmares.dune.net/) It is a "mature" game meaning there's a fair amount of swearing, and the Immortals (moderators) take a fairly hands-off approach.
if you want to play you can go to
http://www.gameaxle.com/ and download the client software (I use PortalGT and log as Rastelzar Morguerat Scooby and Dness) or you can telnet in (if you know how to use telnet it's built into windows) at port 8887
I do not own this game, or have any stock in it, some players are jerks, and it is a PK based MUD, death will happen, it will happen often, but your first 6 hours are safe (with double exp)