Nearly every line of what you wrote dealing with copyright is complete BS. I have no idea where you got that interpretation from.

I'm not a lawyer, but my work deals with patent/copyright issues on a regular basis, and I have sat down with lawyers and gone over these issues. (I also have a little formal coursework on the topic of intellectual property, though not nearly enough to qualify me as any sort of legal scholar.) Also, the last time I sat down with the attorney who handles my patent applications, I asked some general questions relevant to MUDs (at the time, for background about a case involving another game), and they confirmed the general understanding I already had.

Any derivative literary work, CF's content included, is automatically the copyright of the author in the United States. A work by shared authors cannot legally be used without the consent of all parties.

CF is allowed to modify ROM as part of the license agreement, which we have always honored. Our modification does not alter their copyright on their original material. As soon we added a single line, CF had a unique derivative of ROM. Even with all the changes we've made, we're still a derivative work of ROM. Even if we continued to modify the code until every line of ROM was overwritten, we would be a derivative work. The only way to avoid being a derivative would be what is commonly called a "clean room" implementation, where we started with a blank page and wrote our own, new code. We've never done that, or claimed to.

While Carrion Fields did not register any copyrights until much later, that is irrelevant to the ownership of the copyright under U.S. law. Just as you cannot steal the work of an author or artist, you cannot steal the work of a programmer. (If someone hires you, it belongs to the employer, not the employee, but that obviously doesn't apply here.) From the United States Copyright Office:

Copyright protection subsists from the time the work is created in fixed form. The copyright in the work of authorship immediately becomes the property of the author who created the work. Only the author or those deriving their rights through the author can rightfully claim copyright.

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Mere ownership of a book, manuscript, painting, or any other copy or phonorecord does not give the possessor the copyright. The law provides that transfer of ownership of any material object that embodies a protected work does not of itself convey any rights in the copyright.

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The way in which copyright protection is secured is frequently misunderstood. No publication or registration or other action in the Copyright Office is required to secure copyright... Copyright is secured automatically when the work is created, and a work is “created” when it is fixed in a copy or phonorecord for the first time.

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A work that was created (fixed in tangible form for the first time) on or after January 1, 1978, is automatically protected from the moment of its creation and is ordinarily given a term enduring for the author’s life plus an additional 70 years after the author’s death.

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Any or all of the copyright owner’s exclusive rights or any subdivision of those rights may be transferred, but the transfer of exclusive rights is not valid unless that transfer is in writing and signed by the owner of the rights conveyed or such owner’s duly authorized agent.

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A “derivative work,” that is, a work that is based on (or derived from) one or more already existing works, is copyrightable if it includes what the copyright law calls an “original work of authorship.” Derivative works, also known as “new versions,” include such works as translations, musical arrangements, dramatizations, fictionalizations, art reproductions, and condensations. Any work in which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship is a derivative work or new version.

Only the owner of copyright in a work has the right to prepare, or to authorize someone else to create, a new version of that work. The owner is generally the author or someone who has obtained rights from the author."

Carrion Fields has the express, written consent of the DIKU and ROM teams to use their code to create derivative works, so long as we obey their license (or successfully challenge its legality in court). Without similar notice from all parties who made additions to the CF code, no one is allowed to use the CF derivative work as the basis for their own derivative work. (They could, of course, download ROM and begin from there, just as we did, because the ROM team gives you the right to make derivatives in the license. Carrion Fields does not.)

valguarnera@carrionfields.com