The Arena was created to let gnolls and kobolds play a "game" known as the Boomerang Brawl. The word is in quotes because it would qualify only by Roman or Mayan standards - weighted metal boomerangs are thrown at the opposing team. The game also features exploding barrels, as if it weren't dangerous enough. Adventurers who venture into the game are promised appropriate treasure for winning one of these insanely dangerous games, however.
In addition to all of this (and to form the third part of the alliterative title) there have been a number of recent patches and game updates, in the form of classic mission improvements and expanded "hot zones" for extra experience gain. It's a little strange to think of the game as being so old, but it clearly hasn't lost its life just yet.