Logicola

The zorkmid (abbreviated zm) is the fictional unit of currency in the Zork series of interactive fiction computer games. Infocom minted zorkmid coins for inclusion in The Zork Trilogy package released in 1987. They depict the image of Belwit the Flat, ruler of Quendor in 699 GUE. The date on the coin is an anachronism, as in the Zork timeline Quendor was not renamed the Great Underground Empire (“GUE”) until 770.

via Zorkmid Zork Gue Fictional Currency Obverse Games Denominations.