The films tells the story of Arneson in the 1960s and the 1970s, following his war gaming club centered in the Twin Cities and out of the many colleges of the area, but especially the University of Minnesota. Convincingly, the film explains that what would be Dungeons & Dragons—coming to game stores in 1974–actually originated in Arneson’s basement between, roughly, 1969 and 1971. The war gamers, all avid and intelligent, began to experiment with actual individual personality in games. Rather than simply moving troops around a map, why not send in a spy or an assassin?
— Read on theimaginativeconservative.org/2019/09/secrets-of-blackmoor-true-history-dungeons-and-dragons-bradley-birzer.html