MUD2 is the successor of MUD1, Richard Bartle's pioneering multi-user dungeon. Rather than a sequel, it is the result of over 20 years of continuous development, and is still largely based on the game's original code. The game is nominally a roleplaying game, with a very strict set of rules, character classes and levels. Character progress up a ladder of 11 levels until they reach the traditional MUD goal of wiz (wizard or witch). The game's levels are laid out as follows: