Lanefan
Victoria Rules
Not a TTRPG but still too close to home from D&D's viewpoint: for Magic, WotC* once tried to [patent, trademark, copyright - not sure which one applies here] the "tap a card" mechanic, i.e. the act of turning a card sideways in a card game to indicate that card's status had changed or its ability had been used.If your mechanics, processes, or systems are so unique and valuable as to require legal protection, it might be a thing you can protect via a patent. But you don't get a patent just by putting a thing into print - there's a separate application process that most RPGs do not bother to go through. I, personally, cannot think of a single ttrpg that has tried to patent its mechanics.
A year or two and several courtrooms later, this got shot down. But they did try.
* - I forget whether Hasbro had yet bought them out at the time or not.







