Canonballs, Sails or Swords is foremost a classroom game designed to make learning fun. It is pirate themed, 'coz everyone loves pirates, but content non-specific, so can be used in any subject especially to review work in a more interactive fun way than straightforward question and answer. Question and answer, get gold, steal gold and shoot up the other teams fleets. Who doesn't think that learning should be more fun?
It does work (and is a lot of fun) as a desktop game, but it is firstly and foremostly a game to be a tool for adding creativity to the classroom environment.