Found this interesting lengthy - and free - discussion of the nature of original D&D play as a sort of wargame, coming out of 1960s wargame culture - https://www.drivethrurpg.com/product/413382/Muster - reading it now; there's a lot of it! The emphasis on challenge & freedom of choice, no pre-plan, is definitely what I like. I've just started a S&W White Box (also free https://www.drivethrurpg.com/product/190631/White-Box--Fantastic-Medieval-Adventure-Game ) campaign on Roll20, so particularly interested in this sort of thing right now.

One of my big complaints about every editon of D&D since AD&D first is the move away from the wargame roots.

Wargames and roleplaying games don't have a lot of Venn overlap in terms of systems and style.

I have a lot of room in my heart for books on pure RPG theory (especially free ones), and an interest in the history of the hobby, so I'll probably give this a look. But, my initial reaction is skepticism.

I suspect that the decision to move D&D away from it's roots as a miniature wargame was motivated partially by the competitive threat of Runequest, Cyberpunk, Traveller, etc., but mostly by the demands of its players. Dungeon crawling has it's appeal, but its a limited play style that doesn't take full advantage of the differences between an RPG and a wargame. Most people enjoy the classic D&D-style dungeon run, but I don't know how many people would make a lifelong hobby of the game if it was only that.

Also, I see there's a chapter in here about D&D's roots in colonialism.....which doesn't bode well for the rest of the book.