All versions of Inform generate files in Z-code (also called story files) from source code.

These files can then be run by any Z-code interpreter – that is, by any program which properly implements the Z-code virtual machine (or Z-machine) specification. The Z-machine was originally developed by Infocom in 1979 for their interactive fiction titles. Because there is at least one such interpreter for nearly every major and minor platform, this means that the same Z-code file can be run on a multitude of platforms with no alterations.
Andrew Plotkin created an unofficial version of Inform 6 that was also capable of generating files for Glulx, a virtual machine he had designed to overcome many of the limitations of the several-decades-old Z-machine. Starting with Inform 6.3, released February 29, 2004, Inform 6 has included official support for both virtual machines, based on Andrew Plotkin's work. Early release of Inform 7 did not support Glulx, but in August 2006 Glulx support was released.
Inform 6[edit]
Inform 1-6
Paradigm(s) object-oriented, procedural
Appeared in 1993
Designed by Graham Nelson
Developer Graham Nelson
Stable release 6.31 (February 10, 2006)
Influenced by natural language
Influenced Inform 7
OS Microsoft Windows, Mac OS X, Linux, others
License Freeware and Artistic License 2.0
Website http://inform7.com/sources/i6n/ Inform was originally created by Graham Nelson in 1993. In 1996 Nelson rewrote Inform from first principles to create version 6 (or Inform 6). Over the following decade, version 6 became reasonably stable and a popular language for writing interactive fiction.
The Inform 6 system consists of two major components: the Inform compiler, which generates story files from Inform source code, and the Inform library, a suite of software which handles most of the difficult work of parsing the player's text input and keeping track of the world model. The name Inform also refers to the Inform programming language that the compiler understands.
Although Inform 6 and the Z-Machine were originally designed with interactive fiction in mind, a large number of other programs have been developed, including a BASIC interpreter, a LISP tutorial (complete with interpreter), a Tetris game, and a version of the game Snake.
The Inform 6 compiler[edit]
The Inform compiler generates files for the Z-machine or Glulx (also called story files) from Inform 6 source code.
The Inform 6 programming language[edit]
The Inform programming language is object-oriented and procedural. A key element of the language is objects. Objects are maintained in an object tree which lists the parent-child relationships between objects. Since the parent-child relationship is often used to represent location, an object which is the parent of another object is often said to "hold" it. Objects can be moved throughout the tree. Typically, top level objects represent rooms and other locations within the game, which may hold objects representing the room's contents, be they physical items, non-player characters, the player's character, or background effects. All objects can hold other objects, so a livingroom object might hold an insurancesaleman object which is holding a briefcase object which contains the insurancepaperwork object.
In early versions of Inform, objects were different from the notion of objects from object-oriented programming, in that there was no such thing as a class. Later versions added support for class definitions and allowed objects to be members of classes. Objects and classes can inherit from multiple classes. Interactive fiction games typically contain many unique objects. Because of this, many objects in Inform do not inherit from any class, other than the "metaclass" Object. However, objects very frequently have attributes (boolean properties, such as scenery or edible) that are recognized by the Inform library. In other languages this would normally be implemented via inheritance.
Here is a simple example of Inform 6 source code.