Types of Sudoku: A Guide to Every Popular Variant

The classic 9×9 grid is just the beginning. Explore 8 popular Sudoku variants - each with its own twist on the familiar logic.

Whether you've mastered standard Sudoku and want a new challenge, or you're just curious about what else is out there, this guide covers the most popular Sudoku types you'll encounter. Each variant below includes a quick overview, who it's for, and how it differs from the classic puzzle.

Quick links: Sudoku Rules · Strategies · Printable Puzzles

1. Killer Sudoku

Difficulty: ★★★★☆ (Hard)
Also known as: Sum Sudoku, Samunamupure

Killer Sudoku combines the logic of classic Sudoku with the arithmetic of Kakuro. The grid still has 9 rows, 9 columns, and 9 boxes - but instead of pre-filled numbers, you get dotted "cages." Each cage has a target sum, and the digits inside must add up to that sum without repeating.

This means you need two skills at once: the elimination logic of regular Sudoku and the ability to work out which number combinations fit each cage. Many solvers keep a combinations reference table handy (we've built a complete one in our Killer Sudoku guide).

Best for: Experienced Sudoku solvers looking for a step up in difficulty. If you enjoy number puzzles and mental arithmetic, Killer Sudoku is a natural next challenge.

→ Full Killer Sudoku guide: rules, combinations table & strategies

2. Diagonal Sudoku (X-Sudoku)

Difficulty: ★★★☆☆ (Medium)
Also known as: Sudoku X, Cross Sudoku

Diagonal Sudoku follows all the standard rules, plus one extra: the two main diagonals (corner to corner) must also contain the numbers 1–9 without repeating. That's 11 constraint groups instead of the usual 9.

The extra diagonals create more intersection points, which often makes the puzzle easier to start - but harder to finish without contradictions. One misplaced digit and the diagonals will catch it.

Best for: Solvers who want a twist on standard Sudoku without learning entirely new mechanics. If you find regular medium puzzles too routine, X-Sudoku adds just enough complexity to keep things interesting.

3. Samurai Sudoku

Difficulty: ★★★★☆ (Hard)
Also known as: Gattai-5, Butterfly Sudoku

Samurai Sudoku is five overlapping 9×9 grids arranged in a cross or X pattern. Each individual grid follows standard Sudoku rules, but the overlapping regions must satisfy both grids simultaneously. The result is a massive puzzle - typically 369 cells.

The overlapping sections are both a constraint and a gift: solving one grid gives you clues for the next. Samurai puzzles take longer than standard Sudoku (30–90 minutes is typical), but the logical flow between grids is deeply satisfying.

Best for: Puzzle enthusiasts who want a longer, more immersive solve. Great for weekend sessions or printed puzzle books.

4. Jigsaw Sudoku (Squiggly Sudoku)

Difficulty: ★★★☆☆ (Medium)
Also known as: Irregular Sudoku, Nonomino Sudoku

Jigsaw Sudoku replaces the standard 3×3 boxes with irregularly shaped regions. Each region still contains exactly 9 cells and must hold the numbers 1–9 without repeats - but the shapes are different every puzzle.

Because the regions don't follow a predictable grid pattern, your spatial reasoning gets a real workout. You can't rely on the visual shortcuts that work in standard Sudoku. Every puzzle forces you to actually trace the region boundaries.

Best for: Anyone who finds standard Sudoku boxes too predictable. Jigsaw Sudoku is a great way to sharpen your spatial awareness while keeping the core logic intact.

5. Hyper Sudoku (NRC Sudoku)

Difficulty: ★★★☆☆ (Medium)
Also known as: Windoku, NRC Sudoku (named after the Dutch newspaper NRC Handelsblad)

Hyper Sudoku adds four extra 3×3 boxes overlaid on the grid - positioned so they don't align with the standard boxes. Like the original boxes, each extra region must also contain the numbers 1–9 without repeats. That's 13 constraint groups in total.

The additional constraints make Hyper Sudoku puzzles highly interconnected. With more regions overlapping, each placement eliminates more candidates, which can make puzzles faster to solve than they look. The challenge is keeping track of all the extra regions.

Best for: Intermediate solvers who enjoy tightly constrained logic. The extra boxes make for quicker solves with satisfying "cascade" moments where one number triggers a chain of placements.

6. Mini Sudoku (4×4 and 6×6)

Difficulty: ★☆☆☆☆ to ★★☆☆☆ (Easy)
Also known as: Kid Sudoku, Small Sudoku

Mini Sudoku shrinks the grid. A 4×4 puzzle uses digits 1–4 with 2×2 boxes. A 6×6 puzzle uses digits 1–6 with 2×3 or 3×2 boxes. The rules are identical to standard Sudoku - just smaller.

Don't dismiss mini puzzles as trivial. 4×4 grids are perfect for teaching the logic of Sudoku to beginners and kids, while 6×6 puzzles can be surprisingly tricky and make great warm-ups before tackling a harder standard grid.

Best for: Beginners learning the logic for the first time, kids, or anyone wanting a quick 2-minute puzzle break. Also useful as a teaching tool.

7. Mega Sudoku (16×16)

Difficulty: ★★★★★ (Expert)
Also known as: Giant Sudoku, Super Sudoku, Hexadecimal Sudoku

Mega Sudoku scales the grid up to 16×16, using the digits 1–9 plus the letters A–G (or digits 1–16, depending on the publisher). Each row, column, and 4×4 box must contain all 16 symbols exactly once.

With 256 cells and 16 symbols, Mega Sudoku is a serious time commitment. The logic is the same as standard Sudoku, but the sheer scale means more candidates per cell and more complex elimination patterns. A single Mega puzzle can take an hour or more.

Best for: Dedicated puzzle solvers who want endurance-level challenges. If a standard 9×9 feels too quick, 16×16 will keep you busy.

8. Thermometer Sudoku

Difficulty: ★★★☆☆ to ★★★★☆ (Medium–Hard)
Also known as: Thermo Sudoku

Thermometer Sudoku adds "thermometer" shapes to the grid. Along each thermometer, digits must increase from the bulb end to the tip. Standard Sudoku rules still apply - the thermometer is an extra constraint on top of rows, columns, and boxes.

This variant is particularly visual. The thermometers give you immediate ordering information: if a thermometer spans 4 cells, those cells must hold 4 strictly increasing digits. Combined with standard elimination, this creates elegant solving paths.

Best for: Solvers who enjoy visual logic and ordering constraints. Thermometer Sudoku is popular in online puzzle communities and competitions for its clean, satisfying deductions.

Which Variant Should You Try First?

If you're comfortable with standard Sudoku and looking for your first variant, here's a practical starting order:

  1. Diagonal (X-Sudoku) - Minimal rule change, familiar grid. A gentle introduction to variants.
  2. Hyper Sudoku - Same grid, more constraint groups. Satisfying cascades.
  3. Jigsaw Sudoku - Standard rules, unfamiliar shapes. Great spatial training.
  4. Killer Sudoku - Adds arithmetic to elimination. The most popular variant worldwide. Start with our full guide →
  5. Thermometer Sudoku - Adds ordering logic. Popular in competitions.
  6. Samurai Sudoku - Big, interconnected, immersive. Save it for when you have time.
  7. Mega Sudoku - Endurance mode. Only when 9×9 feels too small.

No matter which variant you try, the core skill is the same: systematic elimination. If you're solid on standard Sudoku strategies, you already have the foundation for every variant on this list.

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