DikuMUD

DikuMUD is a multiplayer text-based online role-playing game (MUD) and a reference codebase released in 1990 by the DIKU MUD project at the Danish Institute of Computer Science, now part of the University of Copenhagen. It is one of the earliest and most influential MUD codebases, and many later MUDs were built as derivatives of DikuMUD.

The game uses a data-driven world model in which areas are composed of rooms connected by exits. Each room has descriptions and may contain items or non-player characters (NPCs). Players create characters, choose a class (such as fighter, thief, mage, or cleric), and gain experience by defeating monsters and completing tasks. Combat is real-time, and character statistics such as health, mana, and movement are affected by equipment and spells. The world is configured through text data files that define rooms, objects, mobiles (NPCs), shops, and spells.

DikuMUD code is written in C and designed to be freely redistributed and modified, which contributed to its widespread adoption. Its permissive licensing and data-driven architecture encouraged many forks and clones, including Merc, CircleMUD, ROM, and other descendants, making DikuMUD a common starting point for early MUD development.

Legacy and impact: DikuMUD helped establish a standard approach to building and sharing MUD content in the 1990s. Its design influenced a broad ecosystem of derivatives and contributed to the growth of open-source MUD communities, shaping the development of many text-based online role-playing games that followed.