Z-code file used by the Z-machine game engine , which was used for running text adventure games in the late 1970s and 80s; contains source code for the game; includes graphics referenced in the game unlike previous Z-code file versions; commonly run by a Z-machine interpreter, several programs are listed below.

Z-code files use a programming language called the Zork Implementation Language (Zork was Infocom's first game). The file extensions use a numerical value for the different Z-machine versions that are used to run them. Examples include the .Z1, .Z2, .Z3, .Z4, .Z5, .Z7, and .Z8 extensions. NOTE: Along with Z4 and Z7 files, Z6 file extensions are rarely used.