will respond by describing the results of the action, often the contents of a room if the player has moved within the virtual world. The user reads this information, decides what to do, and enters another short series of words. Examples include "go west", "take flashlight", or "give the letter to the woman then ask her for a book".

Infocom games were written using a programming language called ZIL (Zork Implementation Language), itself derived directly from MDL,