@deckyard/zmachine

A Z-machine interpreter: plays Infocom and Inform games, story files of versions 3, 4, 5, 7 and 8, with Quetzal saves and undo. The machine has no terminal of its own; the host sends it lines and shows what it prints, so a game runs as well in a chat bot or a web page as in a console. Pure Jennifer with no capabilities, so it runs on jennifer-tiny; only open reads a file.

Manual: https://deckyard.github.io/deck-zmachine/

Install

Requires Jennifer 0.25.0 or newer.

jvc add @deckyard/zmachine

jvc vendors the deck to vendor/deckyard/zmachine/. Without jvc, copy src/ from a checkout or a deckyard-zmachine-<version>.tar.gz release archive there, minus the test overlays:

mkdir -p vendor/deckyard/zmachine
cp -R path/to/deck-zmachine/src/. vendor/deckyard/zmachine/
find vendor/deckyard/zmachine -name '*_test.j' -delete

Example

use io;
import "@deckyard/zmachine/" as zmachine;

def m as zmachine.Machine init zmachine.run(zmachine.open("zork1.z3"));
$m = zmachine.send($m, "open mailbox");
io.printf("%s", zmachine.output($m));
# Opening the small mailbox reveals a leaflet.
#
# >
io.printf("%s\n", zmachine.upperWindow($m)[0]);
#  West of House                                               Score: 0  Moves: 1

examples/play.j plays a story in the console:

jennifer run examples/play.j zork1.z3

No game ships with the deck. Zork I-III are published by Microsoft under the MIT licence, the IF Archive holds hundreds of free Inform games, and testdata/lantern.z5 is a two-room test game.

Conformance

The test suite plays the Czech conformance suite in versions 3, 4, 5, 7 and 8 and Praxix in version 5, and every test in both passes. The manual's What is supported page lists what is left out.

Licence

LGPL-3.0-only, see LICENSE. Copyright (C) 2026 mplx <mplx@jennifer-lang.dev>. The test stories in testdata/ carry their own licences; see its README.