On one side: A former chairman of the Joint Chiefs of Staff, former chief of naval operations, 43-year naval officer, Harvard Business School graduate and occasional late-night TV conversationalist. On the other side: A lucky contest winner. In the middle: The greatest Navy-themed board game ever to be turned into a motion picture starring Ray Mabus and Liam Neeson. Not necessarily in that order. Yes, for the low price of $10 (or less), you can enter for a chance to play Battleship against retired Adm. Mike Mullen at the Naval Academy, part of an online fundraiser benefiting The Mission Continues,…