Inform Designer's Manual 4 released

by Jason McIntosh

Graham Nelson has released the long-awaited fourth edition of the Inform Designer's Manual, the documentation/almanac of this powerful, open-source, and extremely multiplatform object-oriented language for creating interactive fiction (a.k.a. text adventure games, a term falling into deprecation as an increasing number of IF works aren't games per se).

You can download the manual as a PDF file for now. I consider it worth reading by anyone interested in the history and design of computer adventure games, whether or not they're interested in actually programming interactive fiction with Inform, due to the long and insightful "The Craft of Adventure" section -- sub-book, really -- that makes up much of the manual's latter half, studying the techniques and trails blazed by pioneers of this genre, from its roots in AI research labs in the 1970s, through the works produced by today's Internet-based IF community.

The whole DM is to Inform as the Camel book is to Perl.

Graham's announcement, as seen on the newsgroup

From: Graham Nelson
Subject: Inform Designer's Manual, 4th Edition
Date: Tue, 01 May 2001 23:25:44 +0100

The Inform Designer's Manual: Fourth Edition
Now downloadable at
(and shortly to become available at

Today is Inform's eighth birthday, and the fourth anniversary of
the third edition of the Designer's Manual, a book which has evolved
continuously since 1993. This new edition is both entirely rewritten
and greatly expanded: freshly edited, checked and proofed, and
fully cross-referenced and indexed. The book is typeset as a 3.1M
PDF document, which can be browsed using the Adobe Acrobat Reader.
(Acrobat is free to download and comes preinstalled on almost all
modern PCs and Apple Macintoshes.) Hyperlinks within the book
allow quick jumping to follow references to other chapters, sections
or pages, to jump from an exercise to its solution or from an index
entry to the passage being indexed. The sections are bookmarked for
convenient browsing.

Even those who aren't interested in Inform as a design system for
interactive fiction may still like to read Chapter VIII, which
begins with a concise history of the genre 1972-1999 and broadens
into a critical study of the literature.

Major improvements since previous editions include:

* Updating to cover Inform 6.21 with library 6/10, including
the new features for strict error checking and Infix
* The example game "Ruins" is doubled in size and completed
into a working game, with a given step by step solution and
a map;
* Fifty further exercises, with complete solutions;
* Three new chapters: first, the rough notes of the old
Translator's Manual have been substantially rewritten to
form a new chapter on writing or customising language
definition files to languages other than English, or to
modified versions of English;
* Secondly, a chapter on the Z-Machine gives far greater
detail on assembly-language programming, and special effects
like sounds and timed keyboard-reading;
* Thirdly, the book concludes with a critical history of
interactive fiction 1972-1999, and essays on game design;
* Many sequences of rules, such as what exactly happens when
the player arrives in a new room, and exactly how the parser
resolves ambiguous noun phrases, are described more fully;
* The semantic rules of the world model are laid out in full;
* References at the end of each section include descriptions
of the 70 or so library extensions by third parties;
* A bibliography gives designer, publisher, date, format and
availability notes on every game discussed in the book;
* Tables at the back of the book, and a simplified Appendix,
make reference easier;
* The index has been entirely remade, annotating entries to
clarify them: thus a typical entry reads "PronounValue
(library routine), 251, 342", with the second reference in
bold face as the Appendix page on which the specification
of the routine appears; and each page reference hyperlinks
to the page in question. (Quite a lot of the long-time
regulars of will find their names in
the index, by the way.)

Despite the six-inch heap of paper proofs and the extraordinary
amount of detailed checking by the editor and proof-readers, it
would be idle to hope that the book is free of error. We kept
finding odd things even in the last week of this two-year revision.
So this is release 4/1 of the Fourth Edition, and I shall feel
reasonably free to make corrected releases as time goes by.
Readers are welcome to email me any errata which turn up.

I should like to express enormous thanks to the team who have
made this book happen: in particular, to Gareth Rees, Andrew
Plotkin, Toby Nelson, Torbjorn Andersson, Dave Doherty,
Michael Baum and many others. And also to thank Mike Berlyn, for
his support and encouragement, and to thank... oh, many other
people, only some of whom are named in the Introduction, but all
of whose contributions were greatly appreciated.

Graham Nelson
University of Oxford
April 1993 -- April 2001

Graham Nelson Oxford, United Kingdom