And now, we can officially say that it is the end of an era: Dave Arneson, co-creator of Dungeons & Dragons, has died, a little over a year after Gary Gygax passed away. Though Gygax's name was much more synonymous with Dungeons & Dragons and roleplaying games in general, Arneson had as much, if not more, of an influence on the early development of the system. Around the same time that Gygax and Perrin were developing their fantasy miniatures game Chainmail, Arneson was developing his own fantasy roleplaying game called Blackmoor. In short order he formed a collaboration with Gygax which evolved into the first edition of D&D, and like Gygax, Arneson continued developing game ideas well after D&D.
I offer many condolences to Arneson's family, and mourn the loss of a man who gave the world a new, unique, and enduring form of entertainment.