Fill in the grid so that every ring and every pair of neighboured circle segments contains the digits 1 through 8. There are no neighbouring cells with consecutive digits.

Fill in the grid so that every ring, spoke and 3x3 box contains the digits 1 through 9. There are no neighbouring cells with consecutive digits.

Fill in the grid so that so that both rings contain the digits 1 through 9. There are no neighbouring cells with the same or with consecutive digits.

Fill in the grid so that so that both rings contain the digits 1 through 9. There are no neighbouring cells with the same or with consecutive digits.

Fill in the grid so that it contains the digits 1 through 6 three times each. There are no neighbouring cells with the same or with consecutive digits.

Fill in the grid so that it contains the digits 1 through 6 three times each. There are no neighbouring cells with the same or with consecutive digits.

Fill in the grid so that both lines (the column and the S-form) contain the digits 1 through 9. There are no neighbouring cells with consecutive digits.

Fill in the grid so that both lines (the column and the S-form) contain the digits 1 through 9. There are no neighbouring cells with consecutive digits.

Fill the grid with the digits 1 to 9. The digits represent the height of the skyscraper in each cell. Each row, column, 3x3-box and cells of the same color have exactly one of each digit. The clues along the edges tell you how many skyscrapers you can see from that vantage point. There are no neighbouring cells with a difference of 3.

Fill the grid with the digits 1 to 9. Each row, column, 3x3-box and coloured region has exactly one of each digit. There are no neighbouring cells with a difference of 3.