From Wikipedia Zork: The Undiscovered Underground (or ZUU for short) is an interactive fiction computer game written by former Infocom Implementors Marc Blank and Michael Berlyn and implemented using the Inform language. The game was released by Activision on August 28, 1997 for free to coincide with the release of Zork Grand Inquisitor. ZUU can be seen as having two goals: promotion of the commercial title Zork Grand Inquisitor, and an attempt to reconcile with die-hard Infocom fans who may have harbored resentment against Activision for their role in buying Infocom in 1985 and subsequent closure of the company in 1989.