Makers of instruments for the Z-machine

frotz, Inc.

Everything that used to come in the box, and a few things that didn't.

In the early 1980s, a company in Cambridge, Massachusetts called Infocom sold computer games made entirely of words. There were no pictures. You typed what you wanted to do, open mailbox, go north, light lamp, and the game wrote back, like a novel that listened. Zork, Enchanter, Planetfall, The Hitchhiker's Guide to the Galaxy: they came in boxes full of maps, letters, and odd little objects, and they were played by hundreds of thousands of people whose computers could barely draw a straight line but whose imaginations had no such limit.

The games outlived the company. The interactive fiction community has kept them playable for forty years and keeps writing new ones. frotz, Inc. makes tools for that work: browser-native instruments for writing, building, inspecting, and shipping games for the Z-machine, Infocom's virtual machine, from brand-new Inform 6 and ZIL games to the original story files. Open source. No installs. No cloud.

Sample transcript
>frotz lamp
The brass lantern begins to glow, casting a warm, steady light.

>inventory
You are carrying:
  a browser
  a story file (lantern.z5)
  a brass lantern (providing light)

>

Product catalog

Fall 2026 edition

A field guide for the newly arrived

For anyone who has never owned a floppy disk
Interactive fiction
A story you play by typing. Also called a text adventure. The graphics are, famously, in your head, where the budget is unlimited.
Infocom
The company (1979–1989) that made the best of them, founded by MIT students and staff who had written Zork for fun on a university mainframe. Bought by Activision in 1986 and closed three years later. Their games are why this page exists.
The Z-machine
Infocom's secret weapon: a virtual computer. Each game was written once, and a small interpreter ran it on the Apple II, the Commodore 64, the IBM PC, and a dozen other machines that agreed on nothing else. Java made the same promise sixteen years later.
Story file
The game itself: a compact file of Z-machine code, like lantern.z5, that any Z-machine interpreter can play. The original Infocom games are story files, and so is anything written in Inform today.
Feelies
The physical extras in an Infocom box: a police dossier, a glow-in-the-dark stone, a pair of cardboard Peril Sensitive Sunglasses, a bag of pocket fluff. Part souvenir, part copy protection. See the tagline above.
frotz
A spell from Enchanter (1983) that makes an object give off light. It is also the name of a much-loved Z-machine interpreter by other people, which we admire and are not.
West of House
Where Zork begins: an open field beside a white house with a boarded front door, and a small mailbox. Generations of players have stood here. So, now, have you.
Grue
What eats you if you wander into the dark without a light. The reason a spell like frotz is worth knowing.
ZIL and Inform
ZIL is the language Infocom wrote its games in. Inform, created by Graham Nelson in 1993, is the one the community built to write new ones. Both compile to the Z-machine, and frotzsmith speaks both.

The company

frotz, Inc. is a software company that does not exist, publishing tools that do. It is the umbrella for a family of open-source instruments for the Z-machine, the virtual machine that ran the great text adventures of the early 1980s and that the interactive fiction community has kept alive ever since.

Every product runs in the browser, works offline, and keeps your files on your machine. Shared code is published under the @frotzinc scope on npm; the tools you type are published under their own names.

The name comes from a spell. In Infocom's Enchanter (1983), frotz causes an object to give off light, which is what these tools are for.

Founded
Never
Headquarters
West of House
Employees
1, part-time
Platform
Z-machine v3–v8, Glulx
License
GPL-3.0+ apps, MIT libraries
npm
@frotzinc/*