Variations Of Sudoku

Nikoli - dell - 25 x 25

Even though the 9 × 9 grid with 3 × 3 regions is the most common, several variations abound: puzzles can be 4 × 4 grids with 2 × 2 regions; 5 × 5 grids with pentomino regions have been published under the name Logi 5; the World Puzzle Championship has featured a 6 × 6 grid with 2 × 3 regions and a 7 × 7 grid with six heptomino regions and a disjoint region. Even the 9 × 9 grid is not always the standard, with Ebb regularly publishing some of those with nonomino regions; the 2005 USA Puzzle Championship had a Soduko with parallelogram regions that wrapped around the outer border of the puzzle, as if the grid were toroidal. Larger grids are also possible, with Dell regularly publishing 16 × 16 grid Number Place Challenger puzzles and Nikoli producing 25 × 25 Sudoku the Giant behemoths.

Daily mail - super sudoku x

Another common variation is for additional restrictions to be enforced on the placement of numbers beyond the usual row, column, and region requirements. Often this restriction takes the form of an extra "dimension"; the most common is for the numbers in the main diagonals of the grid to also be required to be unique. The aforementioned Number Place Challenger puzzles are all of this variant, as are the Sudoku X puzzles in the Daily Mail, which use 6 × 6 grids. The Daily Mail also features Super Sudoku X in its Weekend magazine: an 8 × 8 grid in which rows, columns, main diagonals, 2 × 4 blocks and 4 × 2 blocks contain each number once. Another dimension in use is digits with the same relative location within their respective regions; such puzzles are usually printed in colour, with each disjoint group sharing one colour for clarity.

Other kinds of restrictions can be mathematical in nature, such as requiring the numbers in delineated segments of the grid to have specific sums or products (an example of the former being Killer Su Doku in The Times), demarcating all places arithmetically adjacent digits appear orthogonally adjacent in the grid, providing the parity of all cells, and so on.

Puzzles constructed from multiple Sudoku grids are common. Five 9 × 9 grids which overlap at the corner regions in the shape of a quincunx is known in Japan as Gattai 5 (five merged) Sudoku. In The Times this form of puzzle is known as Samurai Su Doku. Puzzles with twenty or more overlapping grids are not uncommon in some Japanese publications. Often, no givens are to be found in overlapping regions. Sequential grids, as opposed to overlapping, are also published, with values in specific locations in grids needing to be transferred to others.

Alphabet soup

Alphabetical variations, which use letters rather than numbers, have also emerged; of course, there is no functional difference in the puzzle unless the letters spell something. Recent variants have just that, often in the form of a word reading along a main diagonal once solved; determining the word in advance can be viewed as a solving aid. The Code Doku devised by Steve Schaefer has an entire sentence embedded into the puzzle; the Super Wordoku from Top Notch embeds two 9 - letter words, one on each diagonal. It is debatable whether these are true Sudoku puzzles: although they purportedly have a single linguistically valid solution, they cannot necessarily be solved entirely by logic, requiring the solver to determine the embedded words. Top Notch claim this as a feature designed to defeat solving programs.