Sudoku FAQ

How many variants of sudoku are there and what are they?

It is very hard to give a definitive list of types of sudoku puzzles, as new types are always being invented and many come under several names. Here I give a list of the types of sudoku puzzle I know about; if you know of any others please send them to me. The majority of these puzzles are followed by a link to a (free) sample of that sudoku variant puzzle that you can play here at Saidwhat Puzzles online right now.

Sudoku X

The most common sudoku variant, and a special case of extra regions sudoku. Here there are two extra regions, the main diagonals, which give the puzzle the distinctive X-shape. Because of these two extra regions, you need state less givens in order to still create a puzzle with one valid solution that can be reached without guesswork.
Sudoku X puzzle >>>

Slash Sudoku

Slash Sudoku is literally half way between Sudoku and Sudoku X, as it contains one extra region - one of the main diagonals. Therefore it is a hybrid of these two puzzles. I've not seen it published anywhere else other than here. The reason I made it is simple - when I first wrote my Sudoku X creator it was quite slow, so I saved the puzzles that were half-way to being valid (e.g. had one unique diagonal!).
Slash Sudoku puzzle >>>

Killer Sudoku

Killer Sudoku is a significant variant on vanilla sudoku. It has no givens at all to start you off (apart from some kids killer sudoku to make them easier). The row, column and box constraints remain, but the grid is divided into individual regions. You are told what those regions sum up to, and must use that to deduce where each number goes. As such addition is required, and the puzzle is often considered a cross between sudoku and kakuro. You may also need killer sudoku called add-oku, addoku, or even add doku, depending where you look.
Killer Sudoku puzzle >>>

Killer Sudoku X

This is killer sudoku with the X regions from sudoku X added, as such there is even more to consider when trying to solve this puzzle. It is a variant that is not usually seen in mainstream publications such as newspapers and magazines, but it common in sudoku variant magazines.
Killer Sudoku X puzzle >>>

Jigsaw Sudoku

Known variously as Jigsaw Sudoku, Irregular Sudoku, and even ZiguZagu in some places! This sudoku variant has the same number of regions as vanilla sudoku, but the box regions are squished. Rather than being the regular 3 x 3 boxes they may take any shape at all, and hence they fit together like jigsaw pieces to form the complete puzzle, hence it is often called jigsaw sudoku. This is a fun variant, and easier played online where you can clearly use colour to demarcate the different regions.
Jigsaw Sudoku Puzzle >>>

Toroidal Sudoku

Toroidal Sudoku is one of the least common sudoku variants. It is like an even more extreme version of jigsaw sudoku. In toroidal sudoku, the regions can wrap around the top, bottom, left and right of the puzzle, just like your Pacman character going off the edge of the screen and coming back on the other side!

This puzzle is much easier played online where colour is used to show the regions; with thick black and white borders on paper half the battle is working out which cell belongs to each region!
Toroidal Sudoku Puzzle >>>
Toroidal Sudoku X Puzzle

Offset Sudoku

Offset Sudoku is a special type of Extra Regions sudoku. In fact is has an extra 9 regions added to the mix. Not only does each row, column and box have to contain 1 - 9 uniquely, but the order within each box must too. In other words, the first cell in each box must be 1 - 9, and so on for the second, third, fourth... ninth 9 x 9 box.
Offset Sudoku Puzzle >>>

Extra Regions Sudoku

A name for any type of sudoku puzzle that adds extra regions on the standard row, column and box constraints. Thus sudoku X, slash sudoku and offset sudoku are all types of extra regions sudoku. Another common extra regions sudoku puzzle adds four more 9 x 9 boxes into the mix.
Extra Regions Sudoku >>>

We can also create custom sudoku puzzles, for instance for your company marketing or advertising campaign, containing your company initials as extra regions in the sudoku puzzle. Here is an example using 'P' and 'C' as extra regions for Puzzle Club.
Marketing Sudoku >>>

Samurai Sudoku

Samurai sudoku involves the merger of two or more sudoku grids. A common version has five sudokus overlapping in the shape of an X. A good samurai will require you to use the numbers in the overlapping regions to help solve the puzzle, though they can be formed by merging puzzles created in isolation that have a region in common (for instance boxes 1 / 9 or 3 / 7). Some compilers consider this method to be cheating! Furthermore, samurai sudoku are sometimes mixed, so for instance one puzzle within the overall grid will be a jigsaw sudoku, another a sudoku X and so on.
Samurai Sudoku >>> | Buy Samurai Sudoku

Samurai Star Sudoku

This is a type of samurai sudoku that has a much more tightly overlapping set of grids than orthodox samurai puzzles. Rather than having one region overlap, these puzzles share a large number of regions between them. Thus one of the grids is fully embedded in the regions of the other four puzzles, given the grid its shape. This is also known in some places as flower sudoku.
Samurai Star Sudoku >>>

Circle Sudoku

This variant is different more in display than functional terms, displaying as it does the puzzle in a circle format. There are many types and variations available, with differing number of regions and constraints. Many drop the box constraint and simply have spokes and circles to represent the row and column regions. Other constraints are sometimes applied, you may have played variants of this puzzle with eight or nine cells per region, for instance spider sudoku often has nine and re-introduces the box constraint.
Circle Sudoku >>>

Non-Consecutive Sudoku

This variant allows the creation of valid sudoku puzzles with very few given cells, due to the significant constraint that adjacent cells cannot contain consecutive values. This is often used for circular sudoku puzzles or puzzles displayed in that manner, particularly when the constraint applies to the edges top, bottom, left and right of the puzzle too.
Non consecutive sudoku | 12 givens sudoku puzzle

3D Sudoku

As the name suggests, this is sudoku but in 3D. I suspect this one is not for the faint-hearted!

Odd - Even Sudoku

There are a couple of varieties of this puzzle. In one variant, you know whether every square is odd or even - this puzzle is fairly rare and very few givens are needed to the implications of this major constraint.

Another version of the puzzle lets you know whether a certain number of cells are all odd or all even, and you must deduce which it is and then solve the puzzle accordingly. The special cells are usually marked in a different colour.
Play odd even sudoku

Hutosiki

This is very close to sudoku, but is not considered by everyone as a sudoku variant but rather a separate puzzle as it does drop the box constraint and adds a new method. Hutosiki, also called futoshiki, is usually on a 5 x 5, 6 x 6 or 7 x 7 grid, and adds inequality signs to the puzzle. Certain cells are marked as greater or less than one or more of their neighbours, and you must use these constraints to help solve the puzzle.
5x5 Futoshiki Puzzle
7x7 futoshiki puzzle

Greater / Less than Sudoku

This sudoku variant is hutosiki but with the box constraint added back in. Inequalities are used to determine the relations between different cells. There are also variants where the inequalities are placed between cells that are diagonally next to each other, not just horizontally or vertically.

Wordoku

This is not a true variant, in that the puzzle is functionally equivalent to standard sudoku. However the numbers are substituted with letters, usually A - I. There are other various like quiz sudoku, QuizDoku and so on, where certain cells are shaded and must form a word. Some of these puzzles require you to work out the word to get to a valid solution for the puzzle.

Consecutive Sudoku

This is in a sense the opposite of the non-consecutive sudoku: certain cells are marked as being consecutive, traditionally with a slim white bar between the consecutive adjacent cells. This tells the solver that those numbers are consecutive; thus if a cell contains '7' then the consecutively marked adjacent cell contains only 6 or 8. Thus consecutive cells convey a lot of information. This property means that these puzzles can be created with very few givens.

SkyScraper Sudoku

The skyscraper sudoku is an interesting variant of sudoku and is a hybrid with the skyscraper puzzle. In this game, you must work out where to place 1 - 9 under normal sudoku rules, with the addition of the fact that at the start and end of each row and column is a number, which states how many blocks can be seen in that direction. This is based on the numerical value of the numbers, thus nothing can be seen over a 9 and everything can be seen over a 1. There are many interesting rules and deductions that can be made on the basis of the sky scraper regions.

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