Single player game with double fun! If filling up one grid is not enough, how about filling up a grid on both sides at the same time? But watch out! Every puzzle piece has 2 protruding parts that stick through the holes of the grid, making it impossible to place a puzzle piece there on the flip side. When you have found the solution the vertical game board will be filled up completely on both sides with the 11 puzzle pieces back to back. 60 challenges - from easy to extremely difficult!