About Sudoked
Sudoku that understands every step
A logic engine covering 60 named techniques and variants continuously analyzes what comes next, how difficult it is and why it works. This analysis powers Sudoked's hints, its solution-path progress line and six technique-based difficulty levels across 29,696 logically verified puzzles.
- 60techniques and variants
- 6difficulty levels
- 29,696unique puzzles
- 0ads or interruptions
Solution-path analysis
A progress line based on the technique each step requires
Most Sudoku games show only how many cells are empty. Sudoked shows something far more useful: what kind of thinking the remaining cells will require. The progress line above the board contains one segment for every non-given cell. Completed segments record how far you have come; upcoming segments are colored by the difficulty of the logical technique needed to reach that placement.
This is not a generic percentage bar and it is not based on clue count. Sudoked analyzes the current board with the same technique-aware solver that powers its hints. If eliminations such as an X-Wing or a forcing chain are needed before a number can be placed, that complexity carries forward to the cell it unlocks. The segment reflects the hardest logical step required along the way.
The result is a compact map of the puzzle's structure: green and yellow stretches reveal approachable singles; orange and red warn that construction work is coming; dark red marks expert structures; the darkest segments identify forcing-chain territory. As you solve, erase or take a different valid route, the analysis follows the current grid.
Example solution path
Difficulty system
Six levels graded by solving techniques
A puzzle with fewer clues is not automatically harder. Sudoked grades puzzles by solving them logically and measuring the most demanding technique they actually require. Each collection is filtered to create a deliberate learning curve: familiar methods continue to matter while new constructions enter the toolkit.
Easy
Clear, satisfying grids centered on Hidden Singles. Ideal for learning the rules, building scanning rhythm and solving without guesswork.
Medium
Naked Singles join the foundation. Candidate awareness starts to matter, but every step remains direct and readable.
Hard
Introduces Pointing, Claiming and Hidden Pairs — candidate eliminations based on intersections and subsets.
Master
Pairs, triples, X-Wing, Swordfish and strong-link constructions turn candidate notes into a real solving language.
Grandmaster
Wings, uniqueness logic, quads, Jellyfish, BUG and other rare structures reward experienced construction hunters.
Apex
The highest difficulty: Nishio and forcing chains, including multiple, dynamic and nested reasoning for the hardest grids.
Puzzle library
29,696 verified Sudoku puzzles
Sudoked currently includes 29,696 puzzles across Easy, Medium, Hard, Master, Grandmaster and Apex. There are thousands of games at every level, so advancing does not mean repeating the same small pack with its digits rearranged.
The generation and verification system creates uniquely solvable grids, analyzes their full logical path and accepts them only when they fit the intended difficulty profile. That is why the levels feel different for a reason: each step up asks for new techniques, not merely more patience.
Symmetry with variety
The puzzle generator supports eleven clue-layout modes: vertical, horizontal, diagonal, anti-diagonal, bi-diagonal and orthogonal symmetry; 180° and 90° rotational symmetry; full and extended 32-fold symmetry; plus asymmetric layouts. Symmetric givens make a grid visually balanced, while varied layouts keep the solving experience fresh.
Every accepted puzzle still has one solution. Visual elegance never substitutes for logical quality.
Logical hint system
All 60 Sudoku techniques and variants supported by hints
The Hint button does not simply reveal a digit. It searches for the easiest valid next method, highlights the relevant cells, candidates and relationships, and explains the logic. The catalog below expands the solver's technique families into their distinct named variants, including every Unique Rectangle, Unique Loop, BUG, Wing, Ring, X-Chain, XY-Chain and Forcing Chain form that the active hint system can return.
| # | Technique | What the hint can identify |
|---|---|---|
| Foundations | ||
| 1 | Hidden Single | Eight positions for a digit are excluded in a house; resolve the survivor and its 8+12 consequences. |
| 2 | Naked Single | Eight digits are excluded from a cell; resolve the survivor and its 20 peer exclusions. |
| 3 | Pointing | Box-to-line candidate restriction and elimination. |
| 4 | Claiming | Line-to-box candidate restriction and elimination. |
| Locked Subsets | ||
| 5 | Hidden Pair | Two digits restricted to two cells in one house. |
| 6 | Naked Pair | Two matching two-candidate cells that eliminate peers. |
| 7 | Naked Triple | Three cells containing only three combined candidates. |
| 8 | Hidden Triple | Three digits confined to three cells in one house. |
| 9 | Naked Quad | Four cells restricted to four combined candidates. |
| 10 | Hidden Quad | Four digits confined to four cells in one house. |
| Fish | ||
| 11 | X-Wing | A two-row or two-column fish construction. |
| 12 | Swordfish | A three-row or three-column fish construction. |
| 13 | Jellyfish | A four-row or four-column fish construction. |
| AIC Chains | ||
| 14 | Skyscraper | A two-node X-Chain with parallel row or column strong inferences. |
| 15 | 2-String Kite | A two-node X-Chain with row and column strong inferences joined through a box. |
| 16 | Two-Node X-Chain | The general same-digit signature (A=B)-(C=D). |
| 17 | Empty Rectangle | A two-node X-Chain with an empty-rectangle (ERI) grouped strong link. |
| 18 | Three-Node X-Chain | The general L(1)-Wing signature (A=B)-(C=D)-(E=F). |
| 19 | Grouped Three-Node X-Chain | The general L(1)-Wing with one or more grouped sides. |
| 20 | Four+ Node X-Chain | An open single-digit alternating inference chain (AIC) of four or more strong-inference nodes. |
| 21 | XY-Chain | An open alternating inference chain through bivalue cells. |
| 22 | Turbot Fish | A retired historical name for short single-digit chains — now classified as X-Chains. |
| AIC Rings | ||
| 23 | Two-Node Same-Digit AIC Ring | A four-cell single-digit AIC ring — the X-Wing loop — with a verified closing weak inference. |
| 24 | Three-Node Same-Digit AIC Ring | Three single-digit strong nodes with a verified continuous-ring closure. |
| 25 | Grouped Three-Node Same-Digit AIC Ring | Three strong nodes, including a grouped proposition, with a verified continuous-ring closure. |
| 26 | Same-Digit AIC Ring | A single-digit AIC ring whose alternating strong and weak links close into a continuous loop. |
| 27 | Bivalue AIC Ring | A ring whose strong inferences all run through bivalue cells, closed by a verified weak link. |
| 28 | Mixed AIC Ring | An AIC ring mixing bilocal and bivalue strong links, closed by a verified weak link. |
| ALS-XZ Wings | ||
| 29 | XY-Wing | Three bivalue cells using three distinct digits, forming an ALS-XZ construction with an equivalent AIC proof. |
| 30 | XYZ-Wing | One trivalue and two bivalue cells forming an ALS-XZ construction, with the elimination digit present as a candidate in all three. |
| 31 | WXYZ-Wing | Two ALSs spanning four distinct cells and four distinct candidate digits, linked by one RCC. |
| 32 | WXYZ-Ring | Two ALSs spanning four distinct cells and four distinct candidate digits, linked by two RCCs. |
| 33 | VWXYZ-Wing | Two ALSs spanning five distinct cells and five distinct candidate digits, linked by one RCC. |
| 34 | VWXYZ-Ring | Two ALSs spanning five distinct cells and five distinct candidate digits, linked by two RCCs. |
| 35 | UVWXYZ-Wing | Two ALSs spanning six distinct cells and six distinct candidate digits, linked by one RCC. |
| 36 | UVWXYZ-Ring | Two ALSs spanning six distinct cells and six distinct candidate digits, linked by two RCCs. |
| 37 | TUVWXYZ-Wing | Two ALSs spanning seven distinct cells and seven distinct candidate digits, linked by one RCC. |
| 38 | TUVWXYZ-Ring | Two ALSs spanning seven distinct cells and seven distinct candidate digits, linked by two RCCs. |
| Uniqueness | ||
| 39 | Unique Rectangle Type 1 | One rescue cell contains extra candidates; the deadly pair is removed from it. |
| 40 | Unique Rectangle Type 2 | The rectangle's rescue cells share one extra candidate that can be removed from their common peers. |
| 41 | Unique Rectangle Type 3 | The extra candidates combine with other cells to form a naked set in a shared house. |
| 42 | Unique Rectangle Type 4 | A rectangle digit is locked into two rescue cells, allowing the other rectangle digit to be removed. |
| 43 | Unique Loop Type 1 | A longer uniqueness loop has one rescue cell from which the deadly pair can be removed. |
| 44 | Unique Loop Type 2 | Rescue cells in a longer loop share an extra candidate that eliminates from common peers. |
| 45 | Unique Loop Type 3 | Extra loop candidates form a naked set with other cells in a shared house. |
| 46 | Unique Loop Type 4 | One loop digit is locked into the rescue cells, so the other loop digit can be removed there. |
| 47 | BUG Type 1 | One guardian candidate prevents the verified BUG state and must be kept. |
| 48 | BUG Type 2 | Several BUG exception cells share a guardian digit that can eliminate from their common peers. |
| 49 | BUG Type 3 | BUG values combine with nearby cells to form a naked set in a shared house. |
| 50 | BUG Type 4 | Two BUG cells lock an additional candidate in their shared house. |
| Forcing Fallback | ||
| 51 | Forcing Chain | An open mixed X/Y implication chain that proves a placement or elimination. |
| 52 | Nishio | A single-value assumption is disproved by a contradiction. |
| 53 | Cell Forcing Net | Every candidate in one source cell leads to the same conclusion. |
| 54 | Region Forcing Net | Every possible position for a digit in one house leads to the same conclusion. |
| 55 | Dynamic Forcing Chain | Candidate consequences discovered during the chain create new implications. |
| 56 | Dynamic Forcing Chain Plus | A dynamic chain that can use an additional level of sub-rules. |
| 57 | Nested Forcing Chain | Forcing-chain deductions are nested inside another forcing chain. |
Game experience
Features for focused Sudoku solving
Completely ad-free
No banners beside the grid, no pop-ups over a deduction and no video before the next game. Sudoked is Sudoku without advertising, from the board to statistics.
Hints that teach
Relevant cells, candidates, eliminations and chains are shown as a logical explanation, rather than only revealing the answer.
Comfortable on every screen
Responsive controls, pencil marks, undo, mistake feedback, themes and locally saved progress work on phone, tablet and desktop.
No account required
Open the site and play. Your game and personal statistics stay in your browser; there is no registration wall between you and the grid.
Frequently asked questions
About Sudoked
What makes Sudoked different from other online Sudoku games?
Sudoked combines explainable hints for 60 named techniques and variants with a unique progress line that maps the logical difficulty of the remaining solution, six technique-based levels, 29,696 puzzles and a completely ad-free interface.
Does Sudoked explain advanced Sudoku techniques?
Yes. The hint engine ranges from Hidden and Naked Singles through X-Wing, Swordfish, XY-Wing, Unique Rectangles, BUG, large wings and several kinds of forcing chains. It explains the next logical step instead of merely filling a cell.
How does the Sudoku progress line work?
The logical solver analyzes the current grid. Each remaining cell gets a segment colored by the hardest technique needed before that placement, so the solution path and its changing difficulty become visible while you play.
Is Sudoked really free and ad-free?
Yes. It is free to play in a browser with no banners, pop-ups or forced videos. No account or download is required.
Play Sudoku on Sudoked
Choose one of six difficulty levels and start solving in your browser.
Play Sudoked now