“A generic trademark, also known as a generalized trademark or proprietary eponym, is a trademark or brand name that, because of its popularity or significance, has become the generic term for, or synonymous with, a general class of products or services, usually against the intentions of the trademark’s owner.” (from Wikipedia)
I am not a lawyer. This is simply my observation and is not intended as legal advice.

I believe that “Dungeons and Dragons” and “D&D” have become generic trademarks. Just like people may ask for a “Kleenex” when asking for a facial tissue, they often refer to all role playing games as “Dungeons and Dragons“.

Not long ago, when talking to most people, if I said that I played Dungeons and Dragons, they wouldn’t know what I was talking about. In the last five or so years D&D has exploded in popularity and most people know the name Dungeons and Dragons, even if they still don’t know much about it. However, this is the only role playing game they have heard of and may know very little about it. If you play a different TTRPG (table top role playing game) chances are the average person will have never heard of it.

A conversation may go something like this:
“I play _______ every Friday evening.” [Fill in the blank with any TTRPG other than D&D.]
“What is that?”
“It’s a tabletop role playing game”.
“What is that?”
“It’s like Dungeons and Dragons.”
“Oh, I’ve heard of that. Isn’t that where you sit around a table, roll dice and pretend to fight monsters?”
“Yeah, kinda.”

To most people, any game where you sit around a table, roll dice, move little miniature people around and pretend that your character is fighting monsters, is Dungeons and Dragons. And, to tell the honest truth, that isn’t necessarily a bad definition. If you tried to tell your friend what the difference is between D&D and your preferred game it would boil down to your preferred rules. But, the rules aren’t necessary to understand what the game is about, and why we love it.

If you, like me, love fifth edition Dungeons and Dragons, there are most likely some rules that you think need to be changed. You may have some house rules that you use to improve the game. You are probably looking forward to the release of the updated rules that are scheduled to be released this year. You trust that WoTC (Wizards of the Coast) will make changes to improve on the existing rules. When they are released, you will probably switch to playing with the new rules, but you will still be playing Dungeons and Dragons. The same happened when third edition and v3.5 was released. It was all still Dungeons and Dragons.

So what is it when another company takes the Dungeon and Dragons rules (as are available to anyone in the SRD for fifth edition) and makes changes to improve on the existing rules? There is an argument to be made that these versions are still Dungeons and Dragons. Several different companies have done this. Some made major changes and some only added to the basic rules and made minor changes. I say that if you are plying any of these games you are still playing Dungeons and Dragons.

Why does any of this matter?

Many people, myself included, are unhappy with Hasbro, WoTC included, for many things they have done over the last 12 months. So much so that we are uncomfortable giving them any of our money. But we love the current version of Dungeons and Dragons. Of course, we could just continue playing the same game we have been playing for the last 10 years, but the idea of a new improved version is very appealing. So all I am saying is that if this describes you, don’t worry. You can upgrade your version of Dungeons and Dragons to a new and improved version without supporting WoTC. Just switch to one created by a different company. It will still be the same game, but will have changes that the authors think are an improvement. That is the same thing that WoTC is going to be doing with their new release.

I think that the easiest new version to switch to, the one that will be the most like the new version of D&D from WoTC but perhaps even better, is the one that is coming soon from Kobold Press that they are calling Tales of the Valiant. But I am tempted to call D&D 6E.