Three hats: the three parts of creating games

(While I begin by talking about RPGs, I am later going to generalize to all kinds of tabletop and video games - “sit-down games”.) When I used to write lots of articles about RPGs for White Dwarf, Dragon, and other magazines three decades ago, I mostly wrote two kinds of things: game rules, and advice about how to play and especially how to referee Dungeons & Dragons successfully.  I rarely