ColdMUD is a type of MUD server software, similar in many ways to MOO and CoolMUD, from which it is descended. It is a text-based online virtual reality system to which multiple users are connected at the same time. Created by Greg Hudson, it has many similarities to both MOO and CoolMUD. However, there are many important differences from MOO in its embedded, domain-specific programming language, ColdC, and in its implementation of persistence and network services:
- Like CoolMUD, but unlike MOO, ColdMUD's object database is fully disk-based. Whereas MOO's implementation of persistence is based on periodic "checkpoints" during which the complete state of the server's object memory is written to disk, CoolMUD keeps the majority of the object database on disk and keeps a cache of the most frequently used objects in memory, a strategy known as incremental persistence. The ColdMUD implementation of the disk-based object memory is based on Marcus Ranum's work from UnterMUD.
- Unlike MOO, the embedded programming language (ColdC) can be used without using the runtime as a MUD (that is, network accessible) daemon.
Versions through 0.11.0 were written by Greg Hudson and released between 1993 and 1994. Version 0.10 was Hudson's last official release, and the last fully documented ColdMUD server. Colin McCormack assisted in the release of version 0.11.0, which eventually stabilized as 0.11.4.
Subsequently, Jordan Baker added some basic task scheduling primitives, and along with other modifications, this became an unofficial 0.12 version.
At this point Brandon Gillespie forked ColdMUD and it became known as "Genesis". Over the next few years, an active community of contributors made many bug fixes and improvements, but significantly changed the operation of many built-in functions and datatypes. Genesis came to be used by several online communities and games, especially a very large commercial MUD, "The Eternal City".
- Bartle, Richard (2003). Link. New Riders. pp. 11. ISBN 0-13-101816-7. "MOO had two important offspring: Pavel Curtis' LambdaMOO (which was to become a favorite of journalists, academics, and social misfits) and, via CoolMUD, ColdMUD (an attempt to create a software-engineering quality virtual world authoring system)."