Put the numbers 0 through 9 into the triangular cells so that every line (of any length, in three directions) contains every digit not more than once.

Put the numbers 1 through 9 into the triangular cells so that each of 6 large triangles and every line (of any length, even uncontinous) contains every digit not more than once. (Remark: Some lines consist of 8 cells).

Put the numbers 1 through 9 into the triangular cells so that every line (of any length, in three directions) contains every digit not more than once.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box has exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point. The sum of two cells with a bold line between them is always the same, the so called magic number.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box has exactly one of each digit. The same digits can not touch each other diagonally. The clues along the edges tell you how many skyscrapers you can see from that vantage point.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box has exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point. In the blue areas there must always be the same set of digits (possibly in different orders).

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box has exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point. If a clue is cancelled with a red cross then you can't see this number of skyscrapers.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and cells of the same color has exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point.

Fill the grid with the digits 1 to 9. The digits represent the height of the Skyscraper in each cell. Each row, column and 3x3-box will have exactly one of each digit. The green and yellow cells around the grid tell you whether the number of skyscrapers you can see from that vantage point is even or odd. Yellow cells mean that you can see an odd number, green cells mean that you can see an even number.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column and 3x3-box has exactly one of each digit. Yellow cells must contain odd digits, green cells must contain even digits. The green and yellow cells around the 9x9 grid tell you whether the number of skyscrapers you can see from that vantage point is even or odd. The clues in these cells tell you how many skyscrapers you can see from that vantage point.