What does chess represent?

Chess is symbolic of the extent of Felix’s delusion about the ghost of Miranda. Rather than just speaking to her or hearing her voice in the distance, Felix has gone so far as to set-up a chess board on which he convinces himself first that he has taught Miranda how to play, and second that they now regularly play each other when Felix is at home on his own. This is a detail taken from the original in which Miranda and Ferdinand play chess together, indicating that Felix’s interpretations of the play are beginning to influence his delusions about his dead daughter.