Alan (Adventure LANguage) is an authoring system designed to make it easier for people unfamiliar with programming to write IF, or text-adventure games. It was created by Thomas Nilsson and Göran Forslund in 1985 and is continuously updated and maintained by Thomas Nilsson.
The language features a self-documenting, English-like syntax, possibly inspired by COBOL, and several built-in classes of objects commonly used in IF. Version 3 of Alan comes with complete object orientation, inheritance and an extensive library. It supports author defined player syntax and input checks, customization of built-in classes through inheritance, actors than can perform scripted actions, events that can be scheduled, and rules that monitor the game world and triggers when a particular condition arises.
(Version 2 of the system is now considered obsolete as version 3 is fully matured and has entered beta stage.)