Preserving code that shaped generations: Zork I, II, and III go Open Source

Microsoft’s Open Source Programs Office (OSPO), Team Xbox, and Activision are making Zork I, Zork II, and Zork III available under the MIT License.

Zork 1 GitHub repository here

A game that changed how we think about play

When Zork arrived, it didn’t just ask players to win; it asked them to imagine. There were no graphics, no joystick, and no soundtrack, only words on a screen and the player’s curiosity. Yet those words built worlds more vivid than most games of their time. What made that possible wasn’t just clever writing, it was clever engineering.

Beneath that world of words was something quietly revolutionary: the Z-Machine, a custom-built engine. Z-Machine is a specification of a virtual machine, and now there are many Z-Machine interpreters that we used today that are software implementations of that VM. The original mainframe version of Zork was too large for early home computers to handle, so the team at Infocom made a practical choice. They split it into three games titled Zork I, Zork II, and Zork III, all powered by the same underlying system. This also meant that instead of rebuilding the game for each platform, they could use the Z-Machine to interpret the same story files on any computer. That design made Zork one of the first games to be truly cross-platform, appearing on Apple IIs, IBM PCs, and more.

Preserving a piece of history

Game preservation takes many forms, and it’s important to consider research as well as play. The Zork source code deserves to be preserved and studied. Rather than creating new repositories, we’re contributing directly to history. In collaboration with Jason Scott, the well-known digital archivist of Internet Archive fame, we have officially submitted upstream pull requests to the historical source repositories of Zork I, Zork II, and Zork III. Those pull requests add a clear MIT LICENSE and formally document the open-source grant.

Each repository includes:

Source code for Zork I, Zork II, and Zork III.
Accompanying documentation where available, such as build notes, comments, and historically relevant files.
Clear licensing and attribution, via MIT LICENSE.txt and repository-level metadata.
This release focuses purely on the code itself. It does not include commercial packaging or marketing materials, and it does not grant rights to any trademarks or brands, which remain with their respective owners. All assets outside the scope of these titles’ source code are intentionally excluded to preserve historical accuracy.



Source: https://opensource.microsoft.com/blog/2025/...-go-open-source