A Portable Z-Machine Interpreter

Frotz is an interpreter for Infocom games and other Z-machine games. It complies with standard 1.0 of Graham Nelson's specification. It was written by Stefan Jokisch in 1995-1997. It was ported to Unix by Galen Hazelwood. Currently the Unix port is being developed and maintained by David Griffith. The Unix port is also the canonical core version upon which all other ports are based.


  • Compiles and runs without changes on most common flavors of Unix, both open source and not. This includes MacOS X.
  • Portable to many other operating systems and hardware.
  • Plays all Z-code games including V6.
  • Old-style sound support through OSS driver.
  • Config files.
  • User-configurable error-checking.
  • Optional dumb interface.
  • Default use of the Quetzal save file format. Command line option to use the old format.
  • Distributed under the GNU General Public License.
  • Packages available for all popular distributions of Linux and BSD.

    Get Frotz for Unix.

    Source code in the form of a Git repository is available at Frotz's Github page.

    Source code packages are available at Frotz's Sourceforge project page and The Interactive Fiction Archive

    Ports of Frotz to other machines

    Windows Frotz
    A port of Frotz to Microsoft Windows.
    A new port of Frotz (2.43 based) to PalmOS.
    A port of Frotz to KDE.
    A port of Frotz to Windows CE.
    GBA Frotz
    A port of Frotz to Nintendo's Game Boy Advance.
    Infocom Bot
    An AIM chat bot that uses Dumb Frotz. Wired seems to like it.

    Other Links

    Interactive Fiction

    The Interactive Fiction Archive
    The canonical archive for information and specimens of interactive fiction of all kinds.
    The Infocom Homepage
    Lots of information about what was once Infocom (now owned by Activision). Links to where to get new z-machine games and the Old Ones by Infocom.
    The Inform Homepage
    The compiler used to create interactive fiction that Frotz can play.
    Andrew Plotkin's website.
    Also known as Zarf, he is one of the guys who runs The Interactive Fiction Archive. He has also contributed quite a bit to the Interactive Fiction community in many other ways.
    Z-Machine Standards
    Read about a write-once run-many concept created before Java was a twinkle in Sun's eye.
    XYZZYnews is an electronic newsletter about interactive fiction. You'll also find plenty of links to other interactive fiction sites.
    Another 'zine about interactive fiction.
    Baf's Guide to the Interactive Fiction Archive
    Cross-referenced pages on IF platforms, authors, companies, games, genre, and so on. Great for finding a game to suit your mood.
    IF Comp
    Homepage of the Annual Interactive Fiction Competition.
    IF Legends
    A place where lots of different webpages are hosted which have to do with Interactive Fiction.

    Other Interpreters

    A Z-code interpreter for the Palm Pilot and compatibles. Appears to be based on a pre-2.40 version of Frotz.
    A Z-code interpreter written entirely in Perl. Includes some features not found in any other interpreter.
    Another multi-platform/multi-OS zcode interpreter. Uses Glk for I/O.
    Andrew Plotkin's X11 port of ZIP v2.0.7 by Mark Howell. Handles Z-Code versions 1 through 5 and 8.
    Also by Andrew Plotkin, a port of ZIP for Macintosh with System 7 or 8.
    Another ZIP derivative.
    A Z-code interpreter as a Java applet.
    An interpreter for Spectrum +3, Amstrad PCW8000/9000/10 and Amstrad PCW16, written by John Elliott. Might be portable to other CP/M machines.


    A company started by some former Atari programmers and now owns what's left of Infocom.


    This program started as a remake of Mark Howell's Zip, but has grown into a completely new interpreter with ports for lots of platforms.

    Thanks goes to Stefan Jokisch for writing Frotz and Galen Hazelwood for doing the initial work of porting it to Unix. Thanks also to Jim Dunleavy for his optimization to the core Frotz code. Other people to thank include those who uploaded patches to Unix Frotz to the IF-Archive and getting me interested in the inner-workings of interpreters like Frotz, people who posted to Usenet feedback on what I was doing, testers, those who donated the use of machines for porting, sent me patches, etc. These include, but are not limited to:

    Torbjorn Anderson, Timo Korvola, Martin Frost, Mihail Milushev, David Picton, Chris Sullivan, Leonard Richardson, Stephen Kitt, Paul E Coad, Paul Janzen, Brad Town, Jason C Penney, Denis Hirschfeldt, Jacob Nevins, Matteo De Luigi, Steven Frank, Thomas Troeger, and others that I've forgotten.

    Michael Edmonson (author of Rezrov) and Evin Robertson (author of Nitfol) deserve recognition for the ideas that I've borrowed from their programs. Al Petrofsky (creator of dumbfrotz) donated much code to allow Unix Frotz to semi-support V6 games.

    This page was last updated on December 20, 2013