AU is a text based, multi-user dungeon (MUD) set in the fantasy world of Tharel. MUDs have been around since the early 1980`s. This mud started in 1998 and officially opened in early 1999. It is based on the ROM2.4b6 codebase but has many coded features not available with the stock distribution.

Based in the land of Tharel, players have the opportunity to experience the world as one of nine different classes, and 17 different races. All character classes have abilities unique to that class. The mythos of Tharel provides 12 unique gods and goddesses, with a temple dedicated to the worship of each deity. Characters may freely choose their religion. However, religious beliefs in the world of Tharel are the reason for many conflicts and the basis of roleplay for the majority of the playerbase.

Ten different clans are available to characters who join the player killing system. Each of those clans is religiously based and attempts to further the ethos of their god or gods through their roleplay. All player killing is supported through a motivation and justification system. Each attack must fit with the attacking character`s written motivations.

Each justification note is reviewed by the staff of AU to ensure that players stick to their intended roleplay direction. Besides attacking each other, clans can conquer and defile areas, invade other clan halls, and participate in a competition that occurs every two months, the Days of Redemption.

The land of Tharel contains over 11,000 rooms, of which 80% or more are original. Player killing is optional. Roleplay is encouraged, however, within the player killing system roleplay is enforced. An automapper is helpful in learning the lay of the land and understanding the surroundings in all areas.