The Forces of Krill (Zork 1), paperback gamebook, by S. Eric Meretzky
“A fabulous adventure awaits you in the magical land of Zork – where YOU decide what happens!
The powerful warlock Krill has invaded the peaceful land of Zork at a time of unusual weakness. The three legendary Spheres of Power which normally protect the kingdom have disappeared, and Zork’s only hope for survival is to find them.
Can YOU help defend Zork? Or will the kingdom succumb to the evil forces of Krill?”
Note that “S. Eric Meretzky” is actually legendary computer game designer Steve Meretzky.