Grubald the Bold, Matchlick the Mighty, Linklaw the Lucky; all of the great Heroes are busy, laid up, contracted or dead. So it is you who gets to explore a never before seen part of the Great Underground Empire, giving you the chance to finally see a Grue by daylight! This game was developed by Activision and released as a prequel to their adventure "Zork: Grand Inquisitor."
[--blurb from The Z-Files Catalogue]
Zork: The Undiscovered Underground, a prelude to Zork: Grand Inquisitor, is set in the year 1066 GUE. The game is played from the viewpoint of a private in the Inquisition Guard, tasked with exploring a recently discovered area of the Great Underground Empire. The game merges classic "Zorkian" references such as grues and zorkmids with elements created for the newer games, such as Grand Inquisitor.
Feelies here - https://ifdb.tads.org/viewgame?id=40hswtkhap88gzvn
Infocom's trademark was abandoned in 2002, but the IP is stilled owned by Activision. This site exists for the preservation of abandonware.