Sudoku Variants Explained: The 8 Most Popular Types

Q: How do Sudoku variants differ from standard Sudoku?

Standard Sudoku has one rule set: fill a 9x9 grid so every row, column, and 3x3 box contains 1–9. Variants keep that foundation and add one or more extra constraints — additional regions, sum cages, ordering rules, or a larger grid. The core logic stays the same; the extra rules create new solving paths.

Sudoku a Day Blog

By Michel · 4 April 2026

You've solved standard Sudoku. Now what? There are dozens of variants out there, each adding a new twist to the familiar 9×9 grid. Here are the 8 most popular ones — what they add, how hard they are, and which to try first.

1. Killer Sudoku — Difficulty: Hard ★★★★☆

Killer Sudoku replaces pre-filled numbers with dotted "cages." Each cage has a target sum and the digits inside must add up to that sum without repeating. You need both standard elimination logic and basic arithmetic.

It is the most popular variant worldwide. If you enjoy number puzzles beyond pure logic, start here. → Full Killer Sudoku guide

2. Diagonal Sudoku (X-Sudoku) — Difficulty: Medium ★★★☆☆

Diagonal Sudoku follows all standard rules plus one extra: the two main diagonals must also contain 1–9 without repeating. That creates 11 constraint groups instead of 9.

This is the gentlest entry point into variants. Same grid, minimal rule change. → Full Diagonal Sudoku guide

3. Samurai Sudoku — Difficulty: Hard ★★★★☆

Samurai Sudoku is five overlapping 9×9 grids arranged in a cross pattern. Each grid follows standard rules, but the overlapping regions must satisfy both grids simultaneously. Typically 369 cells, taking 30–90 minutes.

Best for when you have time and want an immersive solve. → Full Samurai Sudoku guide

4. Jigsaw Sudoku — Difficulty: Medium ★★★☆☆

Jigsaw Sudoku replaces the standard 3×3 boxes with irregularly shaped regions. Each region still holds the numbers 1–9, but the shapes change with every puzzle. Your spatial reasoning gets a real workout.

Great for solvers who find standard boxes too predictable.

5. Hyper Sudoku — Difficulty: Medium ★★★☆☆

Hyper Sudoku adds four extra 3×3 boxes to the standard grid, positioned so they don't align with the normal boxes. That's 13 constraint groups in total. More constraints often means faster, more satisfying solves.

Also known as Windoku or NRC Sudoku.

6. Mini Sudoku — Difficulty: Easy ★☆☆☆☆ to ★★☆☆☆

Mini Sudoku shrinks the grid to 4×4 or 6×6. Same rules, smaller scale. Perfect for beginners learning the logic, kids, or a quick warm-up before a harder puzzle.

7. Mega Sudoku — Difficulty: Expert ★★★★★

Mega Sudoku scales up to 16×16, using digits 1–9 plus letters A–G. Every row, column, and 4×4 box must contain all 16 symbols. A single puzzle can take an hour or more.

Only attempt this once 9×9 feels too quick.

8. Thermometer Sudoku — Difficulty: Medium–Hard ★★★☆☆ to ★★★★☆

Thermometer Sudoku adds thermometer shapes to the grid. Digits must strictly increase from the bulb to the tip. The thermometers give immediate ordering information that creates clean, satisfying deductions.

Popular in online puzzle communities and competitions. → Full Thermo Sudoku guide

Where to Start

If you're new to variants, try them in this order: Diagonal → Hyper → Jigsaw → Thermo → Killer → Samurai → Mega. Each step introduces one new concept without overwhelming you.

The core skill is always the same: systematic elimination. If you're solid on standard Sudoku strategies, you already have the foundation for every variant on this list.

→ See the full Sudoku Variants guide for deep dives into every type.

Frequently Asked Questions

What is the easiest Sudoku variant to start with?

Diagonal Sudoku (X-Sudoku) is the easiest variant to start with. It uses the same 9×9 grid you already know, with just one extra rule: the two main diagonals must also contain 1–9 without repeating. Nothing new to learn structurally.

What is Killer Sudoku?

Killer Sudoku replaces pre-filled numbers with dotted cages, each showing a target sum. The digits inside each cage must add up to that sum without repeating. It combines standard Sudoku elimination logic with basic arithmetic.

How do Sudoku variants differ from standard Sudoku?

Standard Sudoku has one rule set: fill a 9×9 grid so every row, column, and 3×3 box contains 1–9. Variants keep that foundation and add one or more extra constraints — additional regions, sum cages, ordering rules, or a larger grid. The core logic stays the same; the extra rules create new solving paths.