That equivalence is imperfect since Quake originated as a commercial game and Monolith is presented as a free devkit. With devkits, there is an expectation of à la carte use: If you use the DirectX development kit to make use of Direct3D, you are not obliged to make use of DirectInput or DirectSound. As well, with a video game the primary expected use is entertainment, not creating derivative works. By contrast, it is reasonable for a user to expect a devkit to allow them to create and (where not explicitly forbidden) distribute derivative works, since a devkit's primary expected use is developing derivative works. That is one possible source of confusion.
In my case I wrote to clarify, since two different reasons for limiting the reuse of Monolith assets have been given, whether the first still applies and, if so, which is paramount. I will return to that.
The QBJ3 readme could be construed as permission, since it encourages non-commercial derivative works with attribution (and, unlike the Monolith devkit readme, it does not qualify or restrict that encouragement to QuakeC code) while only forbidding the use of its art assets in commercial products.
Although I notice now that the QBJ3 readme has been revised since its release. The original (dated January 3, 2026) says, beneath "Copyright / Permissions":
while the newest version says:
If that portion of the original readme is construed as permission (it is labeled as such), its revision resembles an attempt to withdraw permission after granting it. That is another possible source of confusion.
To pick up the thread of my original intention in replying, I emphasize "only" in the latter quote because I read it as saying that is the sole reason for limiting asset re-use while, in your post above, you say "the license is about" ensuring Monolith remains its own thing, without mentioning the intention to use them in a game. In other words, are the restrictions on asset reuse solely to keep Monolith monolithic, or do you still "expect to use many of the assets in a commercial game" as the Monolith readme says?
On a tangent: Is it an expected / intended result for mod authors to distribute only their changes and say "Extract this into the Monolith devkit folder, overwriting all files"? Given the incentives, that seems a likely outcome, and one I see no grounds to forbid. If you can't prevent such non-commercial modifications, you might rather allow them, in the same way it is regal to permit the sun to rise at dawn and set at dusk.
