This is one large puzzle, consisting of six different variants of 6x6 sudokus, all linked together by circles. A circle is an outside clue for both adjacent puzzles. Normal 6x6 sudoku rules apply to all sudokus, so each row, column and region must contain 1-6. Outside clues per variant show: Difference Sudoku: The difference of the first two digits in the corresponding direction. Outside-2 Sudoku: Must be placed in one of the first two cells in the corresponding direction. Next-to-6 Sum Sudoku: The sum of all direct neighbours of the digit 6 in the row or column. Skyscraper Sudoku: The number of visible skyscrapers from that side. Higher skyscrapers block the view of lower ones, size being given by the digit. MaxAscending Sudoku: The length of the longest series of ascending digits in the corresponding direction. (E.g. the length of a 1-3-6 series is 3.) First seen odd/even Sudoku: If odd, the first odd number in the corresponding direction; or, if even, the first even number.