He did two pairs of books, White Warlord/Black Baron and Scarlet Sorcerer/Emerald Enchanter. All were printed 1986. They were interesting because they containe

He did two pairs of books, White Warlord/Black Baron and Scarlet Sorcerer/Emerald Enchanter. All were printed 1986. They were interesting because they contained both a single-player game (one in each book) and two-player game (which required both books).