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Once classic Sudoku clicks, you might wonder what else is out there. Quite a lot, it turns out. Sudoku variants keep the familiar rule (each digit once per row, column and box) and add a twist: a different size, an extra region, a sum, or clues drawn between cells. Here are 12 types of Sudoku, what each one changes, and which to try first.
What are Sudoku variants?
12 Sudoku variants at a glance
| # | Variant | What changes | Feels like |
|---|---|---|---|
| 1 | Mini Sudoku | 4×4 or 6×6 grid, digits 1–4 or 1–6 | Gentle |
| 2 | Giant Sudoku | 16×16 grid, digits 1–16 or letters A–P | Long |
| 3 | Sudoku X | Both long diagonals also hold 1–9 | Classic plus |
| 4 | Hyper Sudoku | Four extra 3×3 “windows” also hold 1–9 | Classic plus |
| 5 | Jigsaw Sudoku | Irregular shapes replace the 3×3 boxes | Fresh |
| 6 | Killer Sudoku | Cages with sums, often no given digits | Maths and logic |
| 7 | Samurai Sudoku | Five 9×9 grids overlapping at the corners | Marathon |
| 8 | Greater Than | < and > signs between cells, few or no digits | Puzzle-box |
| 9 | Consecutive | Bars mark neighbours that differ by 1 | Tricky |
| 10 | Thermo | Digits rise along thermometer shapes | Modern |
| 11 | Arrow | Digits on an arrow add up to its circle | Modern |
| 12 | Sandwich | Outside clues give the sum between the 1 and the 9 | Modern |
Different sizes: mini and giant grids
1. Mini Sudoku (4×4 and 6×6)
The same rule on a smaller board. A 4×4 uses the digits 1–4 with 2×2 boxes; a 6×6 uses 1–6 with boxes two rows tall and three columns wide. The American newspaper USA Today has run a 6×6 version. Mini grids are perfect for children, beginners and a two-minute break.
For a full walkthrough with answers, see Sudoku for kids, which solves a 4×4 and a 6×6 step by step.
2. Giant Sudoku (16×16)
Sixteen rows, sixteen columns and sixteen 4×4 boxes, using the numbers 1–16 or the letters A–P. Dell published 16×16 “Number Place Challenger” puzzles, and in 2005 the Radio Times ran a weekly 16×16 “Super Sudoku”. The logic is the same; there is just much more of it.
Extra regions: Sudoku X, Hyper and Jigsaw
3. Sudoku X (diagonal Sudoku)
All the classic rules, plus the two long diagonals must also contain 1 to 9 once each. It is the most common extra-rule variant. The diagonals give you two more units to scan, which often makes a hard puzzle start more easily.
4. Hyper Sudoku
Four extra 3×3 regions, shaded inside the grid, must also contain 1 to 9. Because those windows overlap the normal boxes, they create new hidden singles in places you wouldn’t expect.
5. Jigsaw Sudoku
The 3×3 boxes are replaced by nine irregular shapes of nine cells each, like jigsaw pieces. It’s also called nonomino Sudoku. Your eyes have to unlearn the neat box pattern, which makes even an easy Jigsaw feel fresh.
Sums and overlaps: Killer and Samurai
6. Killer Sudoku
Dotted cages cover the grid, each with a sum in its corner. The digits in a cage must add up to that sum and can’t repeat. Most Killer puzzles have no given digits at all. It first appeared outside Japan in The Times in 2005 and is one of the most popular variants.
Want to try it? Our Killer Sudoku guide explains the rules, the cage combinations worth knowing and the “rule of 45”, and solves the first moves of this exact puzzle.
7. Samurai Sudoku
Five classic 9×9 grids overlap at their corner boxes, arranged like the five on a dice. Each grid follows the normal rules, and the four shared corner boxes belong to two grids at once. In Japan it’s called Gattai 5 (“five merged”). A Samurai is less about one hard step and more about stamina: 369 cells in all.
Clues between cells: Greater Than and Consecutive
8. Greater Than Sudoku
Instead of (or as well as) given digits, < and > signs between neighbouring cells tell you which is bigger. A cell that is greater than both its left and right neighbours can’t be a 1 or a 2, because those two neighbours share a row and must be different digits.
9. Consecutive Sudoku
A bar between two cells means their digits differ by exactly 1 (like 4 and 5). In the usual version, every such pair is marked, so a missing bar is a clue too: those two cells are not consecutive.
Modern favourites: Thermo, Arrow and Sandwich
These “constraint” variants are favourites in puzzle competitions and online solving videos. Each is simple to state and surprisingly deep.
10. Thermo Sudoku
Thermometer shapes are drawn on the grid. Digits must increase from the bulb to the tip. On a five-cell thermometer, for example, the bulb can be at most 5 and the tip at least 5, which rules out digits quickly.
11. Arrow Sudoku
Each arrow starts at a circle. The digits along the arrow must add up to the digit in the circle. A two-cell arrow pointing from a circle containing 3 must hold 1 and 2.
12. Sandwich Sudoku
Numbers outside the grid give the sum of the digits sandwiched between the 1 and the 9 in that row or column. A clue of 0 means the 1 and 9 sit side by side; a clue of 35 means they are at opposite ends.
Which variant should you try first?
| If you… | Try | Why |
|---|---|---|
| are teaching a child or a beginner | Mini 4×4 / 6×6 | Same rule, fewer cells |
| enjoy easy and medium classic puzzles | Sudoku X or Hyper | One extra rule, same techniques |
| want something that feels new | Jigsaw | Breaks the habit of 3×3 boxes |
| like a little arithmetic | Killer, then Arrow and Sandwich | Sums add a second kind of logic |
| have a long, quiet afternoon | Samurai or 16×16 | Big, satisfying projects |
Whatever you choose, the classic techniques from our Sudoku strategies guide carry straight over. Curious how it all began? Read the history of Sudoku.
Frequently asked questions
What is the most popular Sudoku variant?
Killer Sudoku is one of the best known. It first appeared outside Japan in The Times in 2005 and adds cages whose digits must add up to a given sum.
What is the hardest type of Sudoku?
It depends on the puzzle more than the type: any variant can be easy or fiendish. Many solvers find Killer and Samurai puzzles the most demanding because they combine arithmetic or size with classic logic.
What is Sudoku X?
Sudoku X, or diagonal Sudoku, follows the normal rules plus one more: both long diagonals must also contain the digits 1 to 9 once each.
What is a Samurai Sudoku?
Five 9×9 Sudoku grids that overlap at the corners, arranged like the five on a dice. Each grid follows the normal rules, and the shared corner boxes belong to two grids at once. In Japan it is known as Gattai 5.
Should I master classic Sudoku before trying variants?
It helps. Every variant still uses the classic rule, so techniques like hidden singles and pairs carry over directly. Once you can solve medium classic puzzles comfortably, variants are a fun next step.
Sources
- Sudoku: Variants Wikipedia
- Killer sudoku Wikipedia
- Sudoku Wolfram MathWorld (Eric W. Weisstein)