Gemstone IV is a highly developed MUD. It is very old, apparently it launched in 1988. Anyways, it is a Role play enforced, text based, pay to play game. Hit the back button yet?
Overall the game is very fun. It has options and mechanics you will probably never find in another MMO style game. For instance, while you have hitpoints, you also get wounds. It is possible to lose a leg in a fight. To get your leg back you have to go see an player empath (or eat herbs). The empath will then take your leg damage, transferring it to himself, not healing you directly, and then heal himself down, regenerating his leg.
Also, instead of getting experience when you kill a monster, the exp that you earned goes into a pool to get "absorbed" over time. This leads to plenty of role playing around town.
There are various combat maneuvers you can do as well, some of which knock down or stun an enemy. In this game, getting knocked down generally results in death.
The game offers a 30 day free trial, if you supply a credit card. After that it is 14.95 a month + 2.95 for any additional characters. That is right. For a text game. Beyond that there is also a "Platinum" subscription which is far more expensive and puts you on the "awesome" server that the developers pay more attention to and host events on.
Even beyond that are the events that come up, like the Halloween event. It was something like 80 bucks to attend. Seriously, I have never seen such a money hungry company.
Anyways, the game has a pretty strong community and has lead to many many enjoyable hours over the years I have played it off and on. If you are as bored as I am, supply a credit card and check it out. Everyone is willing to help new players.