From the 2014 PDF's Afterword:
Forty years ago, Craig VanGrasstek was fourteen years old, had no idea that the game Dungeons & Dragons existed, and yet managed to produce what is ostensibly the first Dungeons & Dragons variant. This remarkable circumstance results from the informal, collaborative culture of science-fiction fandom, where ideas roam without much regard for inventors and ownership, but with fastidious attention to anything that fascinates fans and stimulates creativity.
In the eighteen pages of rules above, we see the first role-playing game condensed down to its most basic elements, reinvented by someone who learned by playing rather than studying rulebooks. VanGrasstek first encountered the game in February 1974 thanks to Louis Fallert, who had in turn experienced Blackmoor under the tutelage of Arneson's immediate circle in the Twin Cities. Few copies of Dungeons & Dragons were circulating at that point, and thus, in the reaction of VanGrasstek's peers in the Minneapolis science-fiction fandom community, we find some of the earliest commentary on the startling innovations that Dungeons & Dragons introduced. VanGrasstek at the time had the foresight to commit the rules as he understood them to paper: these Rules to the Game of Dungeon, first promulgated in August of 1974.