Sudoku Guides
Long-form articles on the history, mathematics, and craft of Sudoku — where the puzzle came from, why the techniques work, and how to train them deliberately. Read alongside the worked walkthroughs and the technique picker.
They are sequenced as a curriculum rather than a list. Solving Skills runs from a complete beginner's first puzzle through scanning, notation, and the habits that separate fast solvers from stuck ones. Techniques in Depth derives the patterns from first principles, so they become reasoning you can reconstruct rather than shapes you have memorised. History & Mathematics covers where the puzzle came from, how many grids exist, how puzzles are constructed and graded, and what the research on puzzles and cognition actually shows. Reference is the glossary. Reading in order works, but each article stands alone.
Solving Skills
- How to Solve Your First Sudoku: A Complete Beginner’s Guide
A start-to-finish beginner’s guide to Sudoku: the rules in plain terms, where to start on a blank grid, the two techniques that finish most puzzles, and the habits that stop you getting stuck. (11 min read)
- The Right Order to Learn Sudoku Techniques
A practical roadmap through Sudoku solving techniques — which to learn first, why the standard order works, how long each stage takes, and how to know you are ready to move on. (8 min read)
- Cross-Hatching and Scanning: How Fast Solvers Read the Grid
Fast Sudoku solving is a set of trained eye movements. Learn cross-hatching, digit scanning, box counting, and the habits that separate quick solvers from slow ones. (8 min read)
- Pencil Marks Done Right: Candidates Without the Clutter
When to add Sudoku pencil marks, when they hurt, full-candidate versus Snyder notation, and the maintenance discipline that keeps candidates trustworthy. (8 min read)
- The Nine Mistakes That Keep Solvers Stuck
The habits that stall Sudoku solvers: guessing, mis-scanning, over-marking, and the false stalls that look like hard puzzles but are really missed cascades. With fixes. (10 min read)
- How to Get Faster at Sudoku Without Guessing
How to solve Sudoku fast without guessing: speed comes from a fixed scan order, cost-ordered techniques, and pattern recognition — not haste. A practical method to do Sudoku faster. (10 min read)
- What Makes a Sudoku Hard? How Difficulty Ratings Actually Work
Why one paper’s "fiendish" is another’s "medium": what difficulty raters measure, why clue count barely matters, and why technique-based practice beats star ratings. (8 min read)
Techniques in Depth
- Why Naked and Hidden Subsets Work: The Pigeonhole Principle in Action
The logical proof behind Naked Pairs, Hidden Triples, and every subset technique — one pigeonhole argument, plus the duality that makes naked and hidden mirror images. (9 min read)
- X-Wing, Swordfish, Jellyfish: The Fish Family Explained
The fish techniques share one elegant cover-set argument. How X-Wing and Swordfish actually work, where the strange names came from, and why no fish bigger than a Jellyfish is ever needed. (9 min read)
- Beyond Swordfish: Chains, Colouring and the Deep End
What comes after the fish patterns: strong and weak links, simple colouring, XY-Wing, remote pairs and forcing chains — and where deduction ends and search begins. (12 min read)
- Finned and Sashimi Fish: When an Almost-Fish Still Eliminates
The most common reason a fish search comes up empty is one extra candidate. Finned and sashimi fish rescue the pattern — here is the exact fin rule, a worked finned X-Wing, and how to spot one. (10 min read)
- Why Every Proper Sudoku Has Exactly One Solution
What makes a Sudoku "proper", how deadly patterns break puzzles, the techniques that exploit the uniqueness promise, and why some purists refuse to use them. (9 min read)
History & Mathematics
- The History of Sudoku: From Euler to Your Newspaper
Sudoku was not invented in Japan. Trace the puzzle from 18th-century Latin squares through Howard Garns and Dell Magazines to Nikoli, Wayne Gould, and the 2005 boom. (9 min read)
- The Mathematics of Sudoku: Counting Grids, 17 Clues, and NP-Completeness
How many Sudoku grids exist, why 17 is the magic minimum number of clues, and what it means that Sudoku is NP-complete — the real mathematics behind the puzzle. (10 min read)
- How Sudoku Puzzles Are Made
Inside puzzle construction: generating a filled grid, digging out clues while preserving uniqueness, why symmetry is cosmetic, and how a solver assigns difficulty. (11 min read)
- Does Sudoku Help Your Brain? What the Evidence Actually Shows
An honest look at the research on Sudoku and the brain: what training studies find about memory, whether puzzles help prevent dementia, and why "transfer" is the crux of the question. (13 min read)
- Why Easy Sudoku Stops Working Your Brain
A puzzle you have already automated costs your brain less — measurably. What the research on automaticity, neural efficiency and novel learning says about which puzzles are still doing anything. (11 min read)
- Sudoku vs Crosswords: Which Is Better for Your Brain?
Crosswords have more supporting research than Sudoku, and the reason is mostly historical accident rather than superiority. What each puzzle actually demands, and what nobody has tested. (12 min read)
Reference
- The Complete Sudoku Glossary
Every Sudoku term defined in one place — cells, units, and peers; candidates and bivalue cells; naked, hidden, and locked patterns; fish, chains, deadly patterns, and more. (10 min read)