Okay, so, chessboxing is a thing.
The rules in chess boxing are simple. There are 11 rounds and players alternate between boxing and chess. The boxing rounds last three minutes and the chess rounds last four. You win by knockout or checkmate. If neither of those is achieved, the boxer with the highest number of points wins.
The target demographic of chessboxing clubs is, apparently, the same audience that Tyler Durden was after.
Chess boxing partly appeals to the same white-collar people who are drawn to things like fight clubs — mild-mannered professionals that need to let out their angst.