John Ayer wrote on Sun, Mar 20, 2011 12:59 PM UTC:
Blue Queen Chess: A third queen, painted blue (or otherwise uniquely marked), starts on one of the central squares, and can be moved by whichever player has the move. According to the novel in which I first heard of this, it is also possible to capture the blue queen. Finally, confirmation that the game was not a fiction of the novel: http://nielsenhayden.com/makinglight/archives/006433.html