DikuMUD

DikuMUD is a multiplayer text-based role-playing game, which is a type of MUD. It was written in 1990 and 1991 by Sebastian Hammer, Tom Madsen, Katja Nyboe, Michael Seifert, and Hans Henrik Stærfeldt at DIKU (Datalogisk Institut Københavns Universitet)—the department of computer science at the University of Copenhagen in Copenhagen, Denmark.

Commonly referred to as simply "Diku", the game was greatly inspired by AberMUD, though Diku became one of the first multi-user games to become popular as a freely-available program for its gameplay and similarity to Dungeons & Dragons.

Diku's source code was first released in 1990 and became the root of one of the largest trees of derived code from a MUD-like source code package. It has been the basis of a vast number of MUDs, including Avatar, BurningMUD, Daedal Macabre, SlothMUD, TorilMUD, Eris, MUME, Imperial DikuMUD, Northern Crossroads and Arctic MUD, as well as a number of offspring MUD engines such as CircleMUD, Merc, and SMAUG.

The making of DikuMUD was first announced on Usenet by Hans Henrik Stærfeldt March 27, 1990. At the time Tom Madsen, Sebastian Hammer, and Stærfeldt were the only developers, joined by Michael Seifert in June 1990. Stærfeldt stated that their intention was to create a MUD that was less messy than AberMUD, less buggy than LPMud, and more like Dungeons & Dragons.