The first part of the bestselling Zork trilogy, and a close descendant of Adventure, the first work of interactive fiction or text adventure game as the genre was known at the time. Zork I was Infocom's first game, and sold 378,987 copies by 1986. Similarly to Adventure, the game unfolds in a maze-like dungeon, where the user (or adventurer) must battle trolls and solve puzzles in order to find twenty trophies to bring back to the house outside which the game begins.