There were a number of books back then like that (mysteries and such), with the idea that you only revealed the answers to things you couldn't figure out.

As for the game itself, the one part that I have a continued memory about is where you could press the button labeled "Do Not Press". Only doing it a few times gave you the same "nothing happens" message, but being persistent got a different one. Infocom games were so great and full of humor, even the non-Douglas Adams ones.