I realize I'm way out of my comfort zone here. This is not an area where I have a lot of knowledge, but I find this conversation fascinating and have learned a lot about the theories at play here by asking questions. It has really peaked my curiosity... If I cross any lines, either in how I come across or in terms of what someone can answer from a professional perspective, please say so.
So I'm going to ask a question for thought experiment purposes and discussion purposes. The SRD is a blending of the game mechanics with some creative expression. In the fireball spell example you site, there are the functional aspects - how long it takes to charge, the distance it travels, how much damage it does, area of effect - along with some creative expression - the descriptive elements of how you cast the spell and how it appears or sounds.
To take another example - the Potion of Water Breathing. It has functional aspects - duration, how its consumed, game effects - and (a very memorable, in my mind) creative expression - the descriptive appearance, how its brewed, etc.
So does the question become "where is the line between functional game system and creative expression?" And based on that line, what enjoys protection and what doesn't? (And that question is posed rhetorically...please do not try to answer that in regards to the current SRD)
That feels like it would be a very fuzzy line...and it would take a lot of time and care to reimplement the functional aspects of the game system described in the SRD under a new license.
If I understand what you're saying correctly, you believe that the case law states that even though game rules don't enjoy copyright protection, a system like what is outlined in the SRD might be on shakier ground because of the interaction between the system and other copyrighted content. And to what I think is
@S'mon's point above, the blending of system mechanics and creative expression in the form of flavor text. Correct?
Let me play devil's advocate here...
I think you left out some context from your appellate ruling citation. Here is the full paragraph that you pulled from along with the following paragraph:
There is a key citation in here that I think could be critical to how any case would proceed. And that is this:
Further down is this:
I feel like the SRD might be both a framework for expression and possess some expressive qualities. The framework draws from stock fantasy species and archetypes. It does not provide any specific plot or details on how they will interact with the characters in a gameplay session, just the rules for using dice to resolve those interactions when needed. The plot, characters and interactions are either provided by other materials (such as adventure books), developed by the DM and players, or some combination of the two items. It would be hard to argue otherwise.
Are there items in the SRD that could be considered expressive ideas on their own? Yes, I think there are.
The million dollar questions are: where would a court would draw the line, how similar the expressions of some of the ideas would need to be in order to be infringing, and whether these expressions are common tropes for the setting or something unique. And how much work would one need to do to do a clean-room adaptation of the 5E SRD?
That sounds very messy...
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Disclaimer: Not a lawyer. Not legal advice. Did not sleep at a Holiday Inn Express last night...