From the back of the book:
"Now the Darksword saga comes to life in this all-new fantasy roleplaying game that takes you to a time when Magicians and Technologists battled to rule the world."
The book is titled Darksword Adventures; the actual game inside is titled Phantasia.
The book includes fiction and background in addition to the game. The book was intended to support the eponymous novel trilogy plus one.