Yes, it does seem to be the one breaking the most ground: Keys and Phandelver are a pretty well-trodden genre in 5E, Bigby's is probsvly going to look a lot like Fizban's, and Planescape will be a lot like Spelljammer (hopefully linger, anf learning from it)..
To me, it will be a book about game mechanics and subsytem that are not thigly connected to the core. It's a book that needs to be compatible with both a game that exists since 10 years and a new game that it's still not finished. They can not push a big subclass book if that could change the class system in less than one year. Subsystem like a simple dominion and war rules, or some spells and some features that they are use will be usable in OneD&D. Maybe a collection of traps? I think it will be more of a DMs' book than a players' one
I agree, I don't think it will be about modifying core rules (although it will have OD&D compatibility in mind). And, so far as we can ascertain from UA it has fewer subclasses, feats and backgrounds than the Giant and Planescape books. It does have a bunch of spells. It probably has magic items, including deck variants. I think it may contain some adventures featuring or triggered by the deck. "You are imprisoned in a Donjon": Here is the adventure that happens next. "You inherit a kingdom", etc, all potential adventure hooks.
That’s a good point.
Tables of hooks and even short adventures based on some of the card outcomes makes a lot of sense and does sound pretty cool.
One of the reasons DMs are reluctant to use the Deck is that it has a good chance of derailing any storyline. But what if the deck is the storyline?
You don't necessarily have to use those cards. You can add extra cards. Variant Decks are a thing, it would be easy enough to detail them as magic items, and include custom deck tables. The main reason decks aren't used much is because they can, and often do, completely disrupt a campaign. But a custom deck can include only things the DM is happy with and prepared for.
