This puzzle consists of four sets of pieces, each set being represented by squares of a different color.
 
They move orthogonally only, on the 8 by 8 square board.
The pieces cannot be moved individually, but each color-set can be moved simultaneously in a synchronized manner.
 
You play the puzzle by moving one of the squares, thereby moving all pieces of the same color.
However, if any square on the board to which a piece of that color-set is moving is occupied, none of the pieces of that color-set will move.
 
You win when all of the 4 corner squares are occupied.