MAngband is the multiplayer version of Angband, and is a rougelike dungeon game.

Their website can be found HERE - http://www.mangband.org, on their site can be found some useful documentation about the game (most of this info is live), there is also a high-score table for both living and "dead" players.

The game has very simple graphics, but the gameplay is good as any. There is a great deal of commands to learn, though you need few of them to play at the start, but there's a lot to explore as you get deeper into the game. The goal of the game is to fight and kill several monsters that can be found in the Tolkien books. To win the game, you will have to kill "Morgoth The Lord Of Darkness"

Personally I find this game quite entertaining. And altho there are not very many active players, everyone there are mostly glad to help a fellow player in need. Ofcourse, this game require some patience when you are new, and be prepared to die a few times before you get the hang of it.