M.U.L.E.M.U.L.E. was a seminal multiplayer video game written in 1983 by Dan Bunten of Ozark Softscape. It was originally written for the Atari XL and then was ported to the Commodore 64 and the Nintendo Entertainment System. While it played like a game, it was actually an economic simulation taking place on a small colony planet.
Essentially, the game is an exercise in supply and demand economics that is set in space (on the planet Irata, which is Atari backwards) and involves competition between four players. Central to the game is the acquition and use of "M.U.L.E."s (Multiple Use Labor Element) to develop and harvest the player's real estate. The game was revolutionary in the ease with which it allowed multiplayer interaction, but failed as a trend setter.
The game was very popular in its day, and has more recently become a favorite of the retro gaming crowd. Many game designers cite the game as one of the most revolutionary ever and an inspiration for many of their games. Will Wright dedicated his game The Sims, the greatest selling computer game of all time, to the memory of Bunten.