The GSL History of 2008
The Fred Hicks Interview quoted in the opener already indicated, that the Poison Pill must have been a clause that could be sued over, or which could put the viability of the company in jeopardy. In fact, he elaborates on that a little later in the interview:
We knew we couldn’t do 4e support as Evil Hat Productions, because the GSL has a few poison pill clauses in it that would mean — if Wizards of the Coast decided to get into a legal fight with us — that we could lose everything we’ve developed at EHP to the costs we’d be liable for. By spinning off a legally separate entity — One Bad Egg, LLC (“limited liability” was never truer) — we’ve limited the potential damage a lawsuit could do to us.
But how was that clause written? Well, apparently it changed.
mxyzplk, author of Geek-related, was reporting about GSL as it came around in 2008.
In April 2008, a draft version of the GSL was leaked, and it was creating horrible prospects, as mxyzplk put it:
Now, however, Wizards has stated that any company hoping to publish products for their new edition must agree to discontinue any current open licensed products and produce no further open products at all – Dungeons & Dragons related or not. In a phone conversation about 4e licensing with Clark Petersen, president of Necromancer Games, a company representative explained this policy and was adamant that it was not going to change. A number of companies are leveraging the OGL for their independent games, for example the pulp game Spirit of the Century; the gaming community adopted the OGL on good faith and more than 90% of the openly licensed games in existence are using it. This “poison pill” clause means that in exchange for any further involvement with the Dungeons & Dragons game line, a company must abandon any past OGL products and vow not to produce any more.
So the initial planned statement was "If you do GSL, you can't use OGL at all". However, that statement did not make it to the GSL in that fashion - when it came out in June 2008, the paragraph that had many publishers on the fence was toned down to essentially "you can't have the same content under OGL and GSL - to convert it to GSL you have to stop publishing it under OGL. You also can't publish any content under GSL under OGL later." By the end of june, many publishers had announced to not touch 4e at all.
While originally planning to publish 4e material, Necromancer Games backed down from those plans by August 2008. Shortly thereafter, the line of Wizards of the Coast wavered, announcing changes but nothing could be heard. In October 2008, the Fred Hicks Interview happened, making the subsidiary of EHP one of the few third parties that did publish any material under the GSL.
It took until February of 2009 for those announced changes to be published. It was a small change in the text of the GSL. In fact, it was one section that was removed: the old document had 21 sections, the new one had 20.
Mordekai Knode, marketing manager at Tor Publishing in 2012, put it like this in 2012, in a retrospective of the D&D 4th edition:
The third party publishing agreement for the Fourth Edition—the Game System License—didn’t help matters. It had a “poison pill” clause that prevented anyone using it from publishing under the old license—effectively forcing anyone who wanted to publish third-party Fourth Edition supplements to stop publishing anything compatible with the Third Edition. Wizards of the Coast ended up removing a lot of the more restrictive language in the end, but the damage was done.
The vanished section
What was this mysterious vanished section? Well, you'd need to look up the original documents with me. The 4e GSL page went live between 15th June 2008 and 5th July 2008. The page linked the 4e GSL of June 2008 in its original form, and the application to enter the contract with WotC to be allowed to make 4e material under GSL.
As likewise already mentioned, the February 2009 version of the document deleted exactly one section. In the June 2008 version, that section had been labeled "6. OGL; Conversion" and, as we already know, banned the further sale of OGL material that was converted or updated to 4e, and at the same time also banned to port material backward to earlier editions.
There were no further changes to the license as far as I can detect. Only the picture file had been lost between 2015 and 2019. No crawl of 2020 exists, and in early 2021, the page contents were removed like many other 4e material pages.
The Poison Pill:
6. OGL; Conversion
6.1 OGL Product Conversion. If Licensee has entered into the “Open Gaming License
version 1.0” with Wizards (“OGL”), and Licensee has previously published a product under the OGL (each
an “OGL Product”), Licensee may publish a Licensed Product subject to this License that features the
same or similar title, product line trademark, or contents as such OGL Product (each such OGL Product, a
“Converted OGL Product”, and each such Licensed Product, a “Conversion”). Upon the first publication
date of a Conversion, Licensee will cease all manufacturing and publication of the corresponding Converted
OGL Product and all other OGL Products which are part of the same product line as the Converted OGL
Product, as reasonably determined by Wizards (“Converted OGL Product Line”). Licensee explicitly
agrees that it will not thereafter manufacture or publish any portion of the Converted OGL Product Line, or
any products that would be considered part of a Converted OGL Product Line (as reasonably determined by
Wizards) pursuant to the OGL. Licensee may continue to distribute and sell-off all remaining physical
inventory of a Converted OGL Product Line after the corresponding Conversion is published, but will, as of
such date, cease all publication, distribution and sale (and ensure that third party affiliates of Licensee
cease their publication, distribution and sale) of any element of a Converted OGL Product Line in any
electronic downloadable format. For the avoidance of doubt, (a) any OGL Product that is not part of a
Converted OGL Product Line may continue to be manufactured, published, sold and distributed pursuant to
the OGL; and (b) this Section 6.1 will survive termination of this Agreement.
6.2 No Backward Conversion. Licensee acknowledges and agrees that it will not publish
any product pursuant to the OGL that features the same or similar title, product line trademark, or contents
of a Licensed Product.
6.3 Licensee Termination. In the event that any portion of a Converted OGL Product Line is
manufactured or published by Licensee, or a third party affiliated with Licensee, after the first publication
date of a Conversion, Wizards may immediately terminate this License upon written notice.