What is the copyright status of the source code of “Adventure” (also known as Colossal Cave Adventure)?

There is a good record today of the history of Adventure. Specifically: The 1975–1976 Crowther and Woods “350-point version” for PDP-10 Fortran is available.

What is the copyright status of this work? Not just who holds the copyright, but: What license do recipients effectively have in the work? If I derive a work directly from that one, and release the result under e.g. “GNU GPL version 3 or later”, am I violating copyright?

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    I'm voting to close this question as off-topic because it is about a single specific work. Oct 2, 2015 at 4:52
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    Um... we do allow for specific questions - meta.opensource.stackexchange.com/questions/161/…. The source code is available and linked from the Wikipedia article. Determining its license state, even if it turns out to not be FLOSS, can be educational. Why is this offtopic? Oct 2, 2015 at 8:32
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    @curiousdannii this is one of the few definitively answerable questions I see here. I can't imagine why you feel it's off topic.
    – RubberDuck
    Oct 2, 2015 at 11:37
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    Meta Discussion about this post
    – Zizouz212
    Oct 4, 2015 at 17:58
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    I can produce the email from Don Woods if you like. I'd prefer not to expose his email address without his permission. however.
    – ESR
    May 30, 2017 at 5:01

3 Answers 3


If the software is in the public domain, it is effectively free of copyright, and you are free to release a derivative work under any license you want. If it's not, you don't have a license to publish any derivative work.

The oldest existing code for Adventure seems to be from 1976, and a lot was added in 1977. In 1976/7, the copyright act of 1976 was not yet in effect (it went in effect in 1978), so the work is still governed by the copyright law of 1905. That copyright law required all works to be published with a copyright notice for it to be governed under copyright law.

If it was published without a copyright notice, the 1976 and 1977 files are now in the public domain. If it was published with a copyright notice, it won't be until 2072/3 until the material enters the public domain.

For later versions of adventure up to 1989 roughly the same goes, but it also retains copyright protection if it was registered within 5 years of publication.

I have seen no direct indication that the original code had a copyright notice when it was first published. However, conflicting with that narrative is the fact that The Software Toolworks payed "a royalty" to the original authors, which suggests that they did believe the work was copyright protected. One would assume they checked. On the third hand, many others, among which Microsoft, have published Adventure, and according to lore never payed anyone any royalties. On would assume they checked as well.

It is unclear what the exact deal was between The Software Toolworks and Crowther and Woods; whether it consisted of a transfer of copyright - if there even was eligible copyright protection - or that they licensed the work to them.

Crowther and Woods are both still very much alive, and the best way to get certainty about the whole deal is to ask them (and, obligatory, your lawyer, which I am not).

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    Thanks for the comprehensive response. Can you give references to other sources we can read, for the claims about how different conditions imply particular legal effects?
    – bignose
    Oct 4, 2015 at 23:58
  • I always use this handy chart: copyright.cornell.edu/resources/publicdomain.cfm for determining PD status in the US. I'll incorporate some links into to answer tomorrow
    – Martijn
    Oct 5, 2015 at 0:00
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    Isn't it more complicated? I thought prior to the 1976 act, it depended on the state what the copyright terms were? Also, prior to 1980 it wasn't clear that copyright applied to software at all. Opinions went both ways on the matter. Oct 6, 2015 at 3:36
  • I think the sensible conclusion has to be "nobody knows what the copyright situation is", it would have to go to court to find out. Oct 6, 2015 at 3:42
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    I think I remember reading that Crowther doesn't really like to discuss it any more. Oct 9, 2015 at 7:03

The Open Adventure project, distributed as free software under the 2-clause BSD license, reportedly has permission from Don Woods, though there's nothing from Don Woods himself to allow outsiders to verify that permission is granted. No other documentation about permission from other copyright holders in the work is described.

So there is no clear grant of license from all the copyright holders of Colossal Cave Adventure. I can only assume that Open Adventure, if tested on its copyright status, would have to produce clear documentation of license from all copyright holders – documentation that is not presented anywhere I'm aware of – or to rely on an argument that the work entered the public domain.

From what I can gather at the research on Colossal Cave Adventure's history of publication (published in Digital Humanities Quarterly as “Somewhere Nearby is Colossal Cave: Examining Will Crowther's Original "Adventure" in Code and in Kentucky”):

So based on those resources, I think the answer is: the original publication by Crowther and Woods is now in the public domain in the USA, and has been since 2006. Hooray!

Thanks to Martijn's answer laying out many possibilities and directing me to the Cornell University resources.

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    Beware that if it is public domain (and I think it is an "if") then your derivative of the work could also be public domain. You can't release something as GPL unless you own rights to the work. In order for your derivative to be a new work under copyright, you need to make "substantial" changes to it. You can only apply GPL to your project if you've done that. Oct 6, 2015 at 3:45
  • In this specific case, any work of interest is going to either incorporate different executable code (the original PDP-10 Fortran code is not going to run today without heavy modification or complete replacement), or incorporate the work into some non-executable work. Either case would constitute a derived work, by my understanding. So the copyright holder in that derived work can choose to release it under some license or other.
    – bignose
    Oct 16, 2015 at 1:02

This game has been released as open source by Eric S. Raymond, claiming that he has permission of the authors. It's on gitlab.com as announced today in an article on slashdot.org.

  • Note that this is the 1995 version, not the original possibly public domain 1977 version. May 30, 2017 at 0:25
  • “released […] with permission of the authors” — What basis do you have for that claim? The announcement and the history document mention permission only from Don Woods. What of the other authors of the work, where do we find their explicit permission?
    – bignose
    May 30, 2017 at 0:28
  • @bignose The linked gitlab page says at the top, "This code is a forward-port of the Crowther/Woods Adventure 2.5 from 1995, last version in the main line of Colossal Cave Adventure development written by the original authors. The authors have given permission and encouragement to this release." May 30, 2017 at 0:39
  • @GlennRanders-Pehrson: as I've [described](#1917), the only permission mentioned is that of Don Woods, and we don't have anything written by that author explicitly granting permission. That doesn't support a claim that the authors, plural, grant permission; and it doesn't allow anyone to verify that claim. So I think the answer you give here repeats a claim without supporting it.
    – bignose
    May 30, 2017 at 1:41

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