- Designed by Andrew Plotkin [email protected]
- Web site: https://eblong.com/infocom/visi-zork1/
This is the framework for a web app that plays Zork, or another ZIL game, and displays the game state as you play. Call it an exercise in exploratory coding.
To try the Visible Zorker, play Zork 1 or Zork 2. For more about the intent and origins of the project, see my blog post on the subject.
Since the Visible Zorker can play more than one Zork, I have divided it into parts. This repository contains the common framework: the instrumented Z-code interpreter and display layer. Separate repositories contain the information about the game itself:
Thus, the code in this repository is incomplete. It won't work on its own. It's only meaningful as part of the game repo.
The pyana directory
Python scripts which parse the gamedat and gamesrc files and convert them into JSON data in js for the Visible Zorker to load.
Roughly, we need to parse all the ZIL source and the disassembled data, match up numeric addresses with source code names, and write it out in a format that the Javascript app can handle. We use a motley boatload of strategies to accomplish this. The game-info gives us a lot of the needed mappings. Others are based on source code order, memory address order, or whatever else works.
The src directory
Javascript and Typescript sources for the Visible Zorker app itself.
src/visi: The front-end UI of the app. This is React code written in Typescript.src/gnusto: The Gnusto Z-machine engine. This is a part of the Parchment IF web app. I modified Gnusto to track game activity and export it to thevisiUI.src/parchment: Another component of Parchment, responsible for loading the game file and launching the app.src/ifvms.js: Another component of Parchment which acts as a glue layer between Gnusto and the browser display. Also a component which is responsible for the save-file format.src/glkio: The GlkOte IF display library. Also a glue layer which allows Gnusto/IFVMS to use GlkOte.src/lib: Low-level JS libraries used by Gnusto and GlkOte. This includes jQuery.
Yeah, there's a lot of glue layers in there. It's the usual software-engineering story. Gnusto was originally written in 2003 as a browser extension. Then it was modified into a browser application, which was turned into a web site, which was expanded to support other formats besides Z-code. Each of these steps added more layers of abstraction.
I unwound a lot of that work in creating the Visible Zorker. I wanted a simple interpreter engine, and I didn't need the web site or any of the newer formats. But there's still traces of some of the layers.
The css directory
CSS files. Also some icon images in SVG, PNG, and animated-GIF format.
The font directory
Open-source fonts used in the app.
The Visible Zorker is built on a seriously customized version of the Parchment Z-machine interpreter by Marnanel Thurman, Atul Varma, and Dannii Willis.
The fonts used are Courier Prime, Lato, and Libre Baskerville. The header background is copied from Infocom's Zork hint maps.
Zork itself was originally written by Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling. The commercial versions are copyright 1981 (etc) by Infocom, then Activision, then renamed to Mediagenic, then Bobby Kotick bought it and renamed it Activision, then Vivendi bought it and merged it with Blizzard, then Microsoft consumed the lot.
The Visible Zorker is copyright 2025-2026 by Andrew Plotkin. My work on this project is under the MIT license.