21st Slider Puzzle, a free online game

Playing Instructions:
Click on a piece to move it into the empty slot. The solid white piece is the empty slot.
Goal: Arranging the pieces so each pieces is in the correct position.
Hint: Order the numbers sequentially in their natural order starting with 0 in the left upper corner and proceeding right and down. One should do this by sliding either whole columns or whole rows. But there is a caveat. In the original position rows and columns rotate not just slide. This means, for example, that the first element becomes the last when a row is rotated left.