For the original 1983 book of the same name, author Walter Tevis used his own experience and sought out the help of experts like Pandolfini to make sure the depictions of the game were as accurate as possible. However, an onscreen adaptation would require changes to adapt the narrative to a visual medium.
In an interview with independent Russian channel Dozhd, which is only available in its native Russian at this time, Kasparov explained that he was originally approached by the production to play Vasily Borgov, Beth Harmon’s Russian rival. Although he was not able to commit to the time required for the role, Kasparov decided to help the crew with how chess was played. Several consultants, including Pandolfini, were already working on the team, but Kasparov’s experience as a grandmaster and chess prodigy who became the undisputed World Champion at the same age as Beth would be difficult to equal.
The chess grandmaster seemingly worked the most on developing authentic games for Beth to play, which were inspired, but not copied directly, from actual masters of the sport. In one example, he mentions that the season’s final game was an amended version of a match between Vassily Ivanchuk and Patrick Wolff at the 1993 Biel Interzonal Tournament. Wolff even contacted Kasparov after he watched the show and said he recognized his own moves.