Microsoft Open Sources Zork I, II, and III Source Code

Microsoft announced today that it has open sourced the code for the first three Zork text adventure games along with their original build notes, comments, and other historically relevant files, and with clear licensing and attribution.

“Today, we’re preserving a cornerstone of gaming history that is near and dear to our hearts,” Microsoft’s Stacey Haffner and Scott Hanselman write. “Together, 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. Our goal is simple: to place historically important code in the hands of students, teachers, and developers so they can study it, learn from it, and, perhaps most importantly, play it.”

Inspired by Colossal Cave Adventure, the first successful text adventure game for the PDP-10 mainframe computer, developers Tim Anderson, Marc Blank, Bruce Daniels, and Dave Lebling created the original Zork games for the PDP-10 as well and then created the company Infocom to bring them to the first microcomputers in 1980. The Zork games were massive successes, as were many other Infocom games, in an era in which computer graphics were primitive.

Though you can still purchase The Zork Anthology, which includes these titles and several other games, you can compile the source code and run these games for free using a Z-Machine interpreter, as explained by Microsoft. This is solely about game preservation and Microsoft will not try to modernize the games in any way.

Microsoft became the owner of all the intellectual property associated with the Zork titles when it acquired Activision Blizzard in 2023; Activision had acquired Infocom back in 1986.

And to be clear, this isn’t the first release of Zork source code. Archivist Jason Scott uploaded the source code to every Infocom text adventure game, including these Zork titles, to GitHub in 2019. But there were questions about the license, and Activision could have had it pulled at any time. Now, Microsoft owns Activision and thus these Zork titles, so that matter has been settled.