another fiendish puzzle involved the ten tools scattered throughout the game's locations. one of the final puzzles involved marvin asking for a particular tool to use in unjamming the ship's hatch. if the player failed to collect ten, marvin invariably asked for one that was missing. likewise, while the opening section of the game closely resembled the opening scenes of the original radio play and book, there are several actions not in the radio play or book that the player must perform to make the game winnable. other puzzles are based so closely on the book or radio play as to be solvable only by those who are intimately familiar with adams' work. in spite of all of this, "the hitchhiker's guide to the galaxy" was rated as "standard" difficulty by infocom's rating system, though it was advertised to be of expert difficulty.