Stella Schwartz, 16, hopped on the chess bandwagon earlier this year after hearing about the game from her older brother, Hugh, a high school senior in San Francisco. Alex Post, a freshman at Colorado University, started playing in February, after some chess-related videos appeared in his Tik Tok feed; then he got his whole fraternity playing. Many other teenagers and young adults said that they too had recently developed a regular chess habit, although they could not recall how it started. But by all accounts — from players, parents, teachers, website metrics — the game’s popularity has exploded. (In December Chess.com also purchased the Play Magnus Group, a company started by chess world champion Magnus Carlsen that includes a mobile chess app.)

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