The pianist Volker Ahmels regularly organises music festivals in Schwerin, Germany, to remember and to honour ostracised and persecuted musicians. One of these musicians was the composer Arnold Schönberg, who had to flee Austria because he was persecuted by the Nazis. Schönberg is the creator of 12-tone music but he also invented a chess variant, which he called "Coalition Chess". Last week, Volker Ahmels and the cabaret artist Matthias Deutschmann tried their hand at this demanding form of chess.