Quotation marks
There's something wonderful about a story that dispenses with quotation marks. As I mentioned before, I've just finished In the Quick, by Kate Hope Day. Not a quotation mark to be found in Day's novel. Cormac McCarthy's The Road, Kent Haruf's Plainsong. Severance, by Ling Ma; Normal People, by Sally Rooney. (There's a whole Goodreads list called Books Without Quotation Marks, in fact.)
I took this approach with my first few self-published novels. The reader reviews for those books seem divided between people reviewing the story I wrote, and people reviewing the missing quotation marks. (Some readers even believe this to be an editing mistake, I've learned.)
No one can please everyone. What I love about the absence of quotation marks is the immediacy it brings to a story. How it takes a work of fiction and seems to anchor it, to ground it. But I love, too, how it can change the tone and shape of a novel. The Road feels utterly haunted, not least of all because there are no quotes around the characters' dialogue; it truly captures the sense of how shell-shocked these people are, stumbling through a world that has no structure any longer. Plainsong, in a different but similar way, brings to life a world that is unadorned and raw and honest.
So far, at least, The Dark Age has no quotation marks.