Copper was a DikuMUD

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 Staerfeldt at DIKU —the department of computer science at the University of Copenhagen in Copenhagen,...

 based MUD

MUD

A MUD , pronounced , is a multiplayer real-time virtual world, with the term usually referring to text-based instances of these. MUDs combine elements of role-playing games, hack and slash, player versus player, interactive fiction, and online chat...

 launched in June 1991 by Linh Ngo, who was a computer science student at the University of Colorado at Denver. The MUD was named after the machine it ran on, copper.denver.colorado.edu. Andrew Bradford, another UCD student and friend, later joined as a co-implementor. In December 1991 the Copper I source code was released, which was used in creating the popular Merc

Merc (MUD)

Merc is a MUD engine derived from Copper, which in turn was based on DikuMUD. First released in March 1991, DikuMUD served as the basis for many later MUDs....

 codebase, first released in December 1992. In early 1993 Copper II was released, followed by the release of Copper III more than a year later in 1994.

Differences from Other DikuMUDs

Some of the features introduced in Copper were to prohibit player killing and to display player mana

Magic point

Magic points are units of magical power that are used in many role-playing, computer role-playing and similar games as an expendable resource that is needed to pay for magic spells and other abilities, such as special attacks...

, hit points

Health (gaming)

Health is a game mechanic used in role-playing, computer and video games to give value to characters, enemies, NPCs, and related objects. This value can either be numerical, semi-numerical as in hit/health points, or arbitrary as in a life bar....

, and movement points in the command prompt.