The Castle

There are nine possible shapes composed of up to four connected squares, called monomino (1), domino (1), tromino (2) and tetromino (5). Together the shapes cover an area of 29 squares. Using cubes instead of squares you can make solid pattern from them.

Starting with a 5 x 5 square, there are four cubes left to form the "towers of a castle". The computer will randomly choose the position for the towers and you can build the pattern. The shapes may be moved by drag and drop onto the floor or onto another shape. You can rotate the shapes by clicking on one side of the shape. The shape will always rotate around an axis perpendicular to the side you clicked on. It depends on the mouse button pressed whether the shape rotates to the right or to the left.

Click the pattern to get a new one. Only one single pattern is impossible to build. Do you know which ?