Why does sam westing make up the game?

To leave a legacy to all those who have directly or indirectly touched his life. The chosen game format relates to Sam Westing's passion for Chess, whether played on a board with chess pieces, or in real life (business & personal) where the pieces are the lives of people. Everything turned out exactly as he hoped because any master chess player will tell you that they are able to either anticipate an opponent's move, or able to manipulate any unanticipated move to achieve the ultimate goal: to win the game.