Knight Fight

Knight Fight is played on an incomplete Sudoku grid with a odd number of numbers entered. Each player has a differently-colored pencil. The game begins with one player drawing a circle in any empty square and the other player deciding whether to move first or second. After that players take turns to draw circles in spaces without circles which are a knight's move from the opponent's previous move. When no legal moves are available the player who has circled the most numbers wins.