Playing board games online through various tool is a huge part of modern gaming culture. Some of those tools are first-party implementations of the game by the original creators or a license-holder. A lot of them, however, are third-party works.
It's tricky territory and there are a lot of myths circulating around — which is the perfect kind of thing to tackle with a Stack Exchange question.
I think we need some kind of canonical question to cover:
- Is what I'm doing legal, illegal, or a grey area?
- How do I find more information about a specific situation?
- What kind of trouble could I get into (as an end user, at least) if I knowingly or unknowingly use an illegal service?
They key thing is, this is a question for board-game hobbyists about their hobby. I think it's pretty much inevitable that you'll run into this issue if you seriously participate in online play.
It's quite possible that this is a question we need additional expertise to answer in full, but finding a canonical question and answer here — even if it's a redirect to Legal SE or requires extensive quotation of another source — adds value to the site. Because this is the first place I'd look for such an answer, especially if I was looking for one that correctly applied legal principles to nuanced landscape of the board-game world rather than serving up a one-size-fits-all answer.
To be clear, I think this question needs an answer regardless of whether legal questions are on- or off- topic as a whole, because it is an issue that applies to playing games in addition to developing them, and a great answer is likely to involve an experienced hobbyist's understanding of the online-play ecosystem and creator-consumer relationships in the hobby, just as much as an understanding the law. That's... maybe not the most intuitive reasoning, I realize.