I finally finished Peterson's superb 2 volume "Playing at the World"

https://mitpress.mit.edu/9780262552318/playing-at-the-world-2e-volume-2/

(It was a challenge because each footnote would suggest other books I ended up reading...)

When I started reading about the creation of D&D I assumed that the key idea was the invention of the RPG and once invented it would just spread like wildfire. This is only partly true because Peterson talks a lot about role-playing-ish games that existed at about the same time, in the US, UK and Germany, but which didn't catch on: Western Gunfight, Hyboria, Armageddon, Midgard I & II as well as adjacent things like SCA and Coventry.

There are a couple of reasons why D&D took off. One was probably that it was fantasy based and there was a receptive audience primed by a first wave of Tolkien-mania.

But there's another one that I want to rephrase differently from Peterson...