FASA released its Doctor Who RPG in 1985. Its systems were similar to FASA's Star Trek RPG, although it used D6s instead of Star Trek's percentile dice. The box contained three books: The Game Operations Manual, The Players Manual, and A Sourcebook for Field Agents. All three elaborated on the show's canon, although inconsistencies from the televised episodes (for example, the Brigadier retiring in 1977 in "Mawdryn Undead," but Sarah Jane claiming that she joined the Doctor in 1980 in "The Time Warrior") required some changes to the show's official timeline. The RPG text also provides illumination into the Doctor's mysterious homeworld of Gallifrey, although again, the authors had to take some liberties (mixing the legends of Omega and Rassilon, for instance) in order to present a coherent setting.