anchor.diff:  
           player_id was invalid for the provided game
           
  -+ Response 402 (text/plain)
  -
  -        This game has ended
  ++ Response 403 (text/plain)
  +
  +        that game is finished and cannot be modified
   
   ### Play a Card [POST]
   Choose a card value to play from your hand
  
positive.code:         specified game_id not found
  
  
  ## Play the Game [/play/{game_id}{?player_id}]
  
  Make a move or check the current game state
  
  
negative.code:         
      
      
  ## Starting a Game [/game/new]
  
  Start a fight, optionally challenge an opponent
  > If no opponent is defined, they may be challenged later by visiting your game URL
  