--- title: "Learn Sudoku: a path from rules to techniques – Unisu" description: "Start with the rules, get comfortable with pencil marks and choose a technique for the situation you’re working on." lang: "en" canonical: "https://unisu-sudoku.app/en/learn/" --- Learn # Learn Sudoku: a path from rules to techniques Start with the rules, get comfortable with pencil marks and choose a technique for the situation you’re working on. ## A useful starting point ### 1\. Understand the grid Read the three rules and find a first move you can justify. [Read more: 1. Understand the grid](https://unisu-sudoku.app/en/sudoku-rules/) ### 2\. Keep track of possibilities Learn what candidates mean and when to update your notes. [Read more: 2. Keep track of possibilities](https://unisu-sudoku.app/en/sudoku-techniques/pencil-marks/) ### 3\. Look for a pattern Begin with singles, then explore a technique that builds on them. [Read more: 3. Look for a pattern](https://unisu-sudoku.app/en/sudoku-techniques/) Fundamentals Unisu · Oct 26, 2026 ## [How to play Sudoku: rules and your first move](https://unisu-sudoku.app/en/sudoku-rules/) One of each number in every row, column and 3×3 box: learn the rules of classic Sudoku and follow a first certain move. Fundamentals Unisu · Oct 27, 2026 ## [Sudoku pencil marks: track and update candidates](https://unisu-sudoku.app/en/sudoku-techniques/pencil-marks/) A small note records a possibility. Learn how candidates differ from placements and how to keep them up to date. Fundamentals Unisu · Oct 26, 2026 ## [Solve Sudoku without guessing: a repeatable search order](https://unisu-sudoku.app/en/sudoku-without-guessing/) Check nearly full areas, then candidates and singles. Build a routine for finding a move you can explain. Fundamentals Unisu · Oct 26, 2026 ## [Sudoku help: find a logical next move](https://unisu-sudoku.app/en/sudoku-hints/) Stuck on a Sudoku? Follow a checklist, work through one certain move and see how Unisu’s three hint stages explain the next logical step. Fundamentals Unisu · Oct 27, 2026 ## [Sudoku difficulty levels: what makes a puzzle demanding?](https://unisu-sudoku.app/en/sudoku-difficulty-levels/) The techniques you need tell you more than the number of gaps. See how Unisu organizes its 16 game levels. Fundamentals Unisu · Oct 27, 2026 ## [Full House: One gap, one missing digit](https://unisu-sudoku.app/en/sudoku-techniques/full-house/) A Full House has just one empty cell in a row, column or 3×3 box. The one missing digit belongs in that cell. Fundamentals Unisu · Oct 27, 2026 ## [Naked Single: One candidate left in a cell](https://unisu-sudoku.app/en/sudoku-techniques/naked-single/) A Naked Single is a cell with exactly one candidate remaining. Its row, column and box rule out every other digit. Fundamentals Unisu · Oct 27, 2026 ## [Hidden Single: One place left for a digit](https://unisu-sudoku.app/en/sudoku-techniques/hidden-single/) A Hidden Single occurs when a digit has only one possible place in a row, column or box. The cell itself can still have other candidates. Core techniques Unisu · Oct 27, 2026 ## [Locked Candidates: Use the overlap between a box and a line](https://unisu-sudoku.app/en/sudoku-techniques/locked-candidates/) Locked Candidates: when all candidates for a digit in a box lie on one row or column, remove that digit from the rest of that line outside the box. Core techniques Unisu · Oct 27, 2026 ## [Naked Pair: Two cells reserve two digits](https://unisu-sudoku.app/en/sudoku-techniques/naked-pair/) A Naked Pair has two cells in one row, column or box with only the same two candidates. Remove those digits from the other cells in that area. Core techniques Unisu · Oct 27, 2026 ## [Hidden Pair: Two digits have just two places](https://unisu-sudoku.app/en/sudoku-techniques/hidden-pair/) If two digits can appear only in the same two cells of an area, they form a Hidden Pair. Other candidates can be removed from those two cells. Core techniques Unisu · Oct 27, 2026 ## [Naked Triple: Three cells share three candidates](https://unisu-sudoku.app/en/sudoku-techniques/naked-triple/) A Naked Triple has three cells in one area with just three different candidates between them. Remove those digits from the other cells in that area. Core techniques Unisu · Oct 27, 2026 ## [Hidden Triple: Three digits confined to three cells](https://unisu-sudoku.app/en/sudoku-techniques/hidden-triple/) A Hidden Triple occurs when three digits have only three possible cells between them in a row, column or box. Extra candidates in those cells can be removed. Further techniques Unisu · Oct 27, 2026 ## [X-Wing: Two rows, the same two columns](https://unisu-sudoku.app/en/sudoku-techniques/x-wing/) An X-Wing has a digit in exactly two possible cells in each of two rows, in the same two columns. Learn which candidates this pattern rules out. Further techniques Unisu · Oct 27, 2026 ## [XY-Wing: A pivot and two wings](https://unisu-sudoku.app/en/sudoku-techniques/xy-wing/) An XY-Wing connects a pivot cell X/Y to two cells it sees, X/Z and Y/Z. Whichever digit goes in the pivot, one wing must contain Z. Further techniques Unisu · Oct 27, 2026 ## [XYZ-Wing: Three candidates in the pivot](https://unisu-sudoku.app/en/sudoku-techniques/xyz-wing/) An XYZ-Wing has a pivot X/Y/Z and two cells it sees, X/Z and Y/Z. At least one of these three cells must contain Z. Further techniques Unisu · Oct 27, 2026 ## [Swordfish: Follow one digit across three lines](https://unisu-sudoku.app/en/sudoku-techniques/swordfish/) A Swordfish confines a digit’s candidates in three starting rows to exactly three columns. The three required placements use those columns. Further techniques Unisu · Oct 27, 2026 ## [W-Wing: A matching pair joined by a strong link](https://unisu-sudoku.app/en/sudoku-techniques/w-wing/) A W-Wing links two cells with the same candidate pair through a strong link. Follow the example to see how that connection rules out another candidate. Advanced techniques Unisu · Oct 27, 2026 ## [Simple Coloring: Follow one digit in two groups](https://unisu-sudoku.app/en/sudoku-techniques/simple-coloring/) Simple Coloring follows strong links for one digit. When an area has exactly two places for it, one must be true. Alternating groups show those dependencies. Advanced techniques Unisu · Oct 27, 2026 ## [Jellyfish: Four lines form one pattern](https://unisu-sudoku.app/en/sudoku-techniques/jellyfish/) A Jellyfish confines a digit’s candidates in four rows to four columns. Learn how this pattern rules out candidates outside those starting rows. Advanced techniques Unisu · Oct 27, 2026 ## [Unique Rectangle: Avoid a second solution](https://unisu-sudoku.app/en/sudoku-techniques/unique-rectangle/) Unique Rectangle requires a guaranteed unique solution. This example uses four cells in two boxes to show how that condition rules out a candidate. Advanced techniques Unisu · Oct 27, 2026 ## [Finned X-Wing: An X-Wing with an extra possibility](https://unisu-sudoku.app/en/sudoku-techniques/finned-x-wing/) A Finned X-Wing adds a fin to the basic pattern. Remove only candidates that conflict with both the fin and the X-Wing left when the fin is false. Advanced techniques Unisu · Oct 27, 2026 ## [XY-Chain: Link cells with two candidates](https://unisu-sudoku.app/en/sudoku-techniques/xy-chain/) An XY-Chain links cells with exactly two candidates each. Follow the example to see where the shared digit at the two ends can be eliminated. Master class Unisu · Oct 27, 2026 ## [AIC: Alternate strong and weak links](https://unisu-sudoku.app/en/sudoku-techniques/aic/) An AIC connects candidates using alternating strong and weak relationships. An assumption can then be followed along the chain to a certain deduction. Master class Unisu · Oct 27, 2026 ## [ALS: Connect almost locked candidate groups](https://unisu-sudoku.app/en/sudoku-techniques/als/) An ALS is a group of n cells in one area with n+1 distinct digits among their candidates. Two such groups can interact through a restricted common candidate. Master class Unisu · Oct 27, 2026 ## [Forcing Chain: Examine two possibilities separately](https://unisu-sudoku.app/en/sudoku-techniques/forcing-chain/) A Forcing Chain checks both candidates of a cell in separate branches. If both branches force the same elimination, you can apply it with certainty. Master class Unisu · Oct 27, 2026 ## [Nishio: Test an assumption through contradiction](https://unisu-sudoku.app/en/sudoku-techniques/nishio/) Nishio tests one candidate by following the moves it forces. If it leaves a cell with no option or a required digit with no place, reject that candidate. ## Frequently asked questions ### Do I need any experience before learning Sudoku? The three rules are enough to begin. Candidate notes then help you keep track of the possibilities in empty cells. ### Which technique should I learn first? Start with Full House, then Naked Single and Hidden Single. They distinguish a missing digit, a cell with one candidate and a digit with one position. ### Do I have to memorize every technique? No. Learn a method whose reasoning you can follow, then look for it in suitable puzzles. The full catalogue is not an entrance exam. ### How do these guides differ from the app lessons? A guide explains one principle through an example. The app lets you follow guided reasoning and then apply it yourself. ### How can I tell whether I understand a technique? You can explain why the move is forced and which conditions it needs. Recognizing a familiar picture alone is not enough. Download app ## Ready for a puzzle? Take a moment. Download Unisu on your phone. Start a Sudoku or choose a lesson on the technique you want to understand. - [Download on the App Store](https://apps.apple.com/us/app/id6775824061?l=en) - [Get it on Google Play](https://play.google.com/store/apps/details?id=app.unisu.sudoku&hl=en) ![The daily challenge in Unisu](https://unisu-sudoku.app/_astro/en.C-sYR9hJ_1QwI9G.webp) ![A classic Sudoku game in Unisu](https://unisu-sudoku.app/_astro/en.C6DJ1kiE_2dRWDN.webp)