Yeah the book is The Art of Game Design: A Book of Lenses by Jesse Schell. It seems likely this principle was inspired by the book, the author recommends it on

Yeah the book is The Art of Game Design: A Book of Lenses by Jesse Schell. It seems likely this principle was inspired by the book, the author recommends it on a different page. It’s a good book which would also be great as a set of prompt cards IDEO style. Edit: On a whim I googled and it does exist as a card deck as well!