The object is to figure out how to place eight queens on a chess board such that none of them can attack each other. In chess, a queen can attack another piece if it is on the same row, column, or diagonal. To solve this puzzle, therefore, the eight queens must be placed on the board so that no two of them are on the same row, column, or diagonal.
Begin by clicking on a square for the first queen. The queen will show up on the board, and the other squares on the same row, column, and diagonal will be disabled so that no other queens may be placed on those squares. Continue placing queens until it is not possible to place any more.
Source: The Game Website.