CoffeeMUD
CoffeeMUD is a MUD codebase written by Bo Zimmerman. It is a Java engine freely available under the Apache License 2.0.
Overview
CoffeeMUD is designed to be a flexible and extensible MUD engine with a large array set of customizeable gameplay and editing features. The project's goal is to provide a basis for the creation of various fantasy games for both the technically inclined and others.
Technical information
The last version of CoffeeMUD released by Bo Zimmerman is 5.9.0 It was released on Dec 20, 2015.
CoffeeMUD is written completely in the Java programming language. CoffeeMUD 5.9.0 has 704,800 source code lines, excluding comments and blank lines.
It includes world building facilities both from within the game, and from the built-in web site. There are also several scripting languages for game events, including MOBPROG and Rhino.
The engine was originally designed for game building to be done by creating in-game objects in Java and integrating them using the online-creation abilities. This was later extended to allow all aspects of game creation to occur online.