Microsoft makes Zork open-source
72 comments
·November 20, 2025mike1o1
tapoxi
Is it just me or is GitHub having errors again? I keep getting 500s.
gemakelijk
The pages loads for me but I see a "Cannot retrieve latest commit at this time." message.
AdmiralAsshat
Why does Microsoft own the rights to Zork?
csixty4
Activision bought Infocom in 1986, and Microsoft purchased Activision in 2023.
seritools
Infocom was bought by Activision, ActivisionBlizzard was bought by Microsoft.
randall
whoa til microsoft owns blizzard.
entropicdrifter
You're one of today's lucky 10,000. It was huge news at the time. The FTC considered not allowing it and the acquisition got delayed for months while back and forth public debate raged.
charonn0
Because they bought Activision, who owned the rights since the 80's.
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bluedino
I've seen a few things called 'Zork source code' in various places over the years (even on a CD that came with a game programming book of some sort), and copies like this:
https://github.com/MITDDC/zork
What's the lineage here?
jsnell
Zork was originally written at MIT for PDP-10s in an obscure Lisp dialect (MDL). The authors then later formed a company to sell the game on micro-computers. To do it, they built a virtual machine optimized for this purpose, a new Lisp dialect (ZIL) that could compile to the virtual machine, and the ported the game over to that new dialect. Even so, they had to split the game into three parts to fit.
The source you're linking to is the original MDL source. This is about the ZIL source for the three games that the original Zork was split into.
fsckboy
MDL was a dialect of lisp invented by/in part/under Sussman, the originator of Scheme and SICP; what you're calling an obscure dialect was was part of the continuum of a research trajectory, one of a number of experimental languages designed to test out ideas. Sussman got his PhD in 1973 so we're talking about his later work as a student/early work as a postdoc/assistant professor, and Abelson was in the same timeframe, and Guy Steele a half decade junior, and many others in the lab whose names you would also recognize.
dboreham
Was go to say - MIT, dec-10: probably not obscure.
fsckboy
i'm not a complete expert on this, but the dates entailed here trigger clear memories.
the date on the Zork archive you linked to is 1977. in 1977 there was not really yet a notable software market for personal computers based on microcomputer chips, and software development at MIT in that timeframe would have been on Multics or DEC-10 or 20's and (probably not quite) the dawn of Vax-750s
just a couple years later the names on the archive you linked to went on to found infocom to sell this software ported to personal computers, Apple II 6502's or CPM S-100 bus 8080 and Z80s.
the Colossol Cave Adventure game for the PDP-10 had been released (to other institutions that had PDP-10's) just a couple years before and had caught fire in popularity at universities. These people at MIT took the same idea and reimplemented it with embellishments.
CobrastanJorji
Good question, I'm also curious. A quick search shows that there are some differences. The one in this new historicalsources folder has the PLUGH easter egg, but the other one doesn't seem to have it.
But the older version has a "Tomb of the Unknown Implementor," which this new version seems to lack.
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calibas
It is pitch black. You are likely to be eaten by a grue.
vunderba
Love it. I use a grue reference on 404s to my blog.
esafak
I wonder if grue was taken from Nelson Goodman's Fact, Fiction, and Forecast. https://en.wikipedia.org/wiki/New_riddle_of_induction
MarkusQ
Yes. Because it is pitch black and therefore you can not determine it's color (plus, the fact that you haven't been eaten by one yet does not justify the conclusion that you won't be). It's also a play on Gardener's "unexpected hanging paradox".
ayaros
This is great, but I'd rather they make Windows 11 open-source instead.
jsheard
Funnily enough you can easily find the Windows XP source code on GitHub. Not endorsed by Microsoft of course, but they've ignored it sitting on their own service for years, along with ignoring all the modern Windows and Office piracy tools which are also on GitHub. Microsoft works in mysterious ways.
nebula8804
If AGI ever comes close to fruition I can't wait to just dump this code into some AI, tell it to fix all security bugs and make it work on M Series processors. Would finally achieve a computing environment that would be perfect for me. Until then, I will continue to dream.
Night_Thastus
If we ever get to the point of having a tool that could do something that complex, we're well past the point of using human-written operating systems or using M-series processors.
Which is to say, very, very, very far away.
pavlov
Why not use AI to make ReactOS better? Is there something in original Windows XP that ReactOS doesn’t want to implement?
iddan
Most of the money to be made is by licensing software to organisations that can afford the risk of pirating (practically anything bigger than SMBs: enterprises, governments, armies, etc). The moat of everyone used to your platform worths a lot more. So they just regulate enough so it won’t seem like they don’t give a shit at all.
ChicagoDave
Scott: Do the whole library of Infocom games!
abtinf
The license says it’s copyright 2025. How does that work? Shouldn’t the copyright be something like 1977?
QuantumNomad_
IANAL but copyright is typically the year of first publication.
I could see this being important here in two ways:
1. If the source code of Zork has not been made available to the public before, then now is the year of publication.
2. If Zork source code has previously been made available to the public, perhaps the version published here has had changes made, in which case now is the year of publication of this version of the source code.
I assume that when Microsoft opens source code they have a team of lawyers that have solid legal arguments for what the copyright year should be in each case.
Therefore, maybe it’s even possible legally that
3. Even if source code was previously made available, and even if no changes were made in any way since then to any of the included source code or other files, perhaps just the act of using a different license is in its own way part of how copyright applies. Publishing something under a specific license in $CURRENT_YEAR does not retroactively make the license apply before the time at which it was made available under that license and so perhaps an argument could be made that copyright year in a license includes taking that into consideration.
Blamklmo
[dead]
Aman_Kalwar
Wow, didn’t expect this from Microsoft. Amazing to see classic game code being made accessible for learning
ghssds
This is exactly the kind of thing Microsoft likes to opensource: old, crusty, and obsolete. Let's compare. When ID Software opensourced Doom a few years after it's initial release, there was still some life in it and it spawned a myriad of forks and new developments continuing to this day. An active community formed around it. When Microsoft opensourced MSDOS, an opensource clone had existed for so long it was only of interrest to archeologists and historians. It was as whitered and lifeless as Zork is.
katspaugh
So Zork was written in Lisp? It had to be!
---
<ROUTINE V-ADVENT ()
<TELL "A hollow voice says \"Fool.\"" CR>>leoc
From one perspective ADVENT is just SHRDLU turned inside out, after all. (Though of course from another perspective it's a fancier WUMPUS.)
('ADVENT' is https://en.wikipedia.org/wiki/Colossal_Cave_Adventure , for anyone who isn't familar.)
agiacalone
MDL, actually, which was derived from LISP.
drob518
I’m curious why they chose MDL rather than Lisp for it. Sure, it would have been ancient MACLISP or whatever, but why not leverage what was already in wide use at MIT at the time?
arnonejoe
I read a while back it’s a language called zil based on MDL.
https://the-rosebush.com/2025/07/studies-of-zil-part-2-how-d...
PaulHoule
… right, Activisiom bought Infocom in the 1980 s…
OhMeadhbh
Yeah. I had to walk down memory lane to try to remember who bought whom as well. I completely forgot that Activision/Blizzard is a subsidiary of Microsoft Gaming these days.
theoldgreybeard
So derivative works are possible, who will be the first to attach Zork to the OpenAI API?
simonmales
I love the idea that these can live forever in apt/rpm repositories.
throwuxiytayq
It seems likely that the entirety of Zork (world state and the possible actions to transform it) is already learned by the model. Which means that there is a grue in there, too. Not good. I’m starting to re-think the doomer argument...
https://github.com/historicalsource/zork1 Direct link to the repository