Feelies
Like most other Infocom games, Zork Zero comes with feelies: a printed calendar titled "The Flathead Calendar 883" with portraits and biographies of the Twelve Flatheads (also usable as a 1989 calendar), folded blueprints with a yellow Post-it note attached, and a scrap of parchment. Since completing the game requires information revealed only in these feelies, they serve to discourage unauthorized copying.
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