Master Sudoku techniques

Master Sudoku with expert-level techniques

When advanced patterns are not enough, these expert techniques use chains, coloring, uniqueness logic, and deeper structural analysis to break the hardest boards.

This page covers Jellyfish, Unique Rectangles, Empty Rectangles, W-Wings, Simple Coloring, X-Chains, XY-Chains, and Remote Pairs. Each technique is demonstrated on a fixed board.

What this page demands

These are the techniques that separate expert solvers from advanced ones. Each slide isolates the pattern on a fixed board.

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  • Read chain logic across multiple strong and weak links.
  • Use uniqueness constraints to eliminate candidates that would create multiple solutions.
  • Follow coloring patterns that mark cells as true or false across the grid.
  • Master the hardest fish and wing extensions.

Master walkthroughs

These are the techniques that separate expert solvers from advanced ones. Each slide isolates the pattern on a fixed board.

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Digit 4 spans four rows across four columns. The red 4s outside the pattern must go.

4-row fish

Jellyfish

Jellyfish extends X-Wing and Swordfish to four rows. When one candidate is locked into the same four columns across four rows, that candidate can be removed from the rest of those columns.

How to read it

  1. 1Track one candidate and find four rows where it only appears inside the same four columns.
  2. 2Treat those rows and columns as a closed network for that candidate.
  3. 3Remove the candidate from every other cell in the four target columns.

What it unlocks

Jellyfish completes the basic fish family. It is rare, but when it appears it clears large numbers of candidates at once.

The logic scales directly from X-Wing. Four rows, four columns, one candidate. Everything else in those columns gets cleared.

Technique 1 of 8

Master technique questions

Do I need master techniques for most puzzles?

No. Most puzzles up to hard difficulty can be solved with basic and advanced techniques. Master techniques are needed for expert and extreme puzzles.

What is the best way to learn chains?

Start with Simple Coloring on a single digit, then move to X-Chains. Once alternating links feel natural, XY-Chains and Remote Pairs follow logically.