MUDs are text-based games. Here's a sample from whatever I'm doing right now:
Yes, I am a Jedi. My lightsaber is ruby-colored.> nw
A hazy tunnel (se,n)
> n
As you move further down the tunnel to the north, you notice an
eerie glow emanating from an alcove on either side of you. Two huge
guards step out in front of you, blocking your path. Their mouths,
the only part you can see of their otherwise armour-clad bodies,
smile and hiss at you. The red glow from their visor helm warns you
that these guards are demon spawn.
> Your concentration breaks, letting your lesser Force shield dissipate away.
taunt
You reach out with the force and taunt Daemon Guard.
You reach out with the force and taunt Daemon Guard.
>
You concentrate on the ebb and flow of the Force about you, searching
for the subtle patterns within the fragile web. With the force of your
will alone you gather the Force about you in a cocoon of pure energy.
You pummeled Daemon Guard into tiny fragments.
You reach out and deflect the attack!
Daemon Guard struck, but did no damage to you.
You feint to the side and then strike with ruby death.
I also rambled a little about 3k here and here.
There are a lot of guilds (and thus a lot of playing styles), some better than others: changeling, jedi, monk, bard, cyborg, juggernaut, necromancer, bladesinger, elemental, knight, priest, breed, gentech, mage, witch, sii.
It is a silly game. What I do is chat with people and wander around killing things.
If I like you well enough, I'll help you get settled in the game. When you make a character, just contact me--I'm either Dyanara, Kaindell, or Chaostrophy. The command to see if someone is online is "finger"--yes yes, you can all finger me all day if you like. I won't even know. So log on, "finger dyanara" (or kaindell or chaostrophy), and if I'm online, "tell dyanara Hi I am from NC save me from the evils of the world!" And also who you are so I know if I like you enough to help you or if I should lead you into some horrible monster's den and leave you there. ^_~
Check out 3k.org for info (the address for connecting to the game is 3k.org, port 3000), and if you like, gameaxle.com has Portal, a free MUD client. I use it, but I may switch to zmud someday. Tinyfugue is another popular client. I don't remember what Mac users use--I used to have Rapscallion on my Macs, though.
Here, I'll go through how to add a Portal profile for 3k:
Open the program and you'll see a blue window with lots of buttons.
Click the "player profiles" button.
Click "add profile."
Enter in a player name (one you'd like for yourself) but no password. (There is a chance the name you want would be taken--you can MSN me or Ariel to ask if it is, or just hope it's not.)
Click the "MUDS" button. Choose 3kingdoms; it should be at the top.
Click the "create new from scratch" button.
Click "close."
Your profile is now selected on the left. Click "login online" to start up 3k.
After you've made your character, you may want to disconnect (in the upper left, the plug/outlet button, to the right of the left-pointing red arrow) and edit your player profile to include the password you chose.