Shapedoku Articles · Page 3

Play smarter, think sharper

Guides for new players, strategies to solve faster, and the real benefits of a daily puzzle habit. Everything you need to get more out of Shapedoku and Sudoku.

Expert Sudoku8 min read

ALS-XY-Wing Sudoku: Three Almost Locked Sets Working Together

ALS-XY-Wing Sudoku links three Almost Locked Sets through restricted common candidates. Learn the pattern, proof, and endpoint eliminations.

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Expert Sudoku8 min read

Mutant Fish Sudoku: Mixed Houses in Advanced Fish Logic

Mutant Fish Sudoku mixes rows, columns, and boxes on both sides of a fish. Learn the base-cover idea, verification steps, and common mistakes.

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Expert Sudoku8 min read

Kraken Fish Sudoku: Combining Fish Patterns With Chains

Kraken Fish Sudoku uses chains to extend a fish beyond direct fin eliminations. Learn the core idea, branch logic, and a safe way to verify targets.

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Advanced Sudoku8 min read

Finned Swordfish Sudoku: How to Find and Verify the Pattern

Finned Swordfish Sudoku adds a local fin to a three-line fish. Learn the base and cover sets, the two-case proof, and safe eliminations correctly.

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Advanced Sudoku7 min read

Sashimi X-Wing Sudoku: How the Incomplete Fish Still Eliminates Candidates

Sashimi X-Wing Sudoku is a finned X-Wing with a missing corner. Learn the pattern, the conditional logic, and where eliminations stay valid.

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Advanced Sudoku7 min read

Turbot Fish Sudoku: A Practical Guide to the Four-Candidate Chain

Turbot Fish Sudoku links two strong links with one weak link. Learn how to spot the four-candidate chain and make safe eliminations correctly.

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Sudoku variants7 min read

12x12 Sudoku: Rules, Symbols, and Solving Strategy

12x12 Sudoku expands the grid to 144 cells. Learn the 12-symbol rules, 3x4 box structure, candidate tactics, and a manageable solving workflow.

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Sudoku basics6 min read

4x4 Sudoku: Rules and Beginner Strategy

4x4 Sudoku uses digits 1 to 4 in rows, columns, and 2x2 boxes. Learn the rules, simple solving steps, and how the mini grid builds logic skills.

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Sudoku variants7 min read

Butterfly Sudoku: Rules and Solving Strategy

Butterfly Sudoku combines four overlapping 9x9 grids. Learn the shared-region rules, central solving tactics, and a clear workflow for the layout.

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Sudoku variants7 min read

Sohei Sudoku: Rules and Solving Strategy

Sohei Sudoku uses four overlapping 9x9 grids. Learn how the shared corner boxes work, where to start, and how to pass deductions between grids.

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Sudoku variants7 min read

Flower Sudoku: Rules and Solving Strategy

Flower Sudoku links several overlapping 9x9 grids. Learn the rules, how shared boxes transfer information, and a practical solving workflow.

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Sudoku variants7 min read

Sukaku Sudoku: Rules and Solving Strategy

Sukaku Sudoku replaces given digits with candidate lists. Learn the rules, how to read pencilmarks, and how to solve the full grid logically.

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Puzzle comparison7 min read

Sudoku vs Dominosa: Symbol Placement and Domino Pairing Compared

Compare Sudoku vs Dominosa by candidate logic, unique pairs, adjacency, domino tiling, and the deduction style that makes each grid puzzle satisfying.

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Puzzle comparison7 min read

Sudoku vs Slant: Candidate Placement and Loop-Free Lines Compared

Compare Sudoku vs Slant by candidate placement, numbered intersections, loop-free diagonals, cycle prevention, and the solving habits each puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Skyscrapers: Set Logic and Visibility Clues Compared

Compare Sudoku vs Skyscrapers by set logic, visibility clues, candidate placement, ordering, height logic, and the solving habits each puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Yajikabe: Placement Logic and Connected Shading Compared

Compare Sudoku vs Yajikabe by symbol candidates, arrow counts, connected black regions, 2x2 restrictions, and the local-to-global reasoning each rewards.

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Puzzle comparison7 min read

Sudoku vs Mathrax: Number Placement and Diagonal Arithmetic Compared

Compare Sudoku vs Mathrax by row and column uniqueness, diagonal arithmetic clues, parity, candidate logic, and the reasoning style each puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Easy as ABC: Symbols, Empty Cells, and Outside Clues

Compare Sudoku vs Easy as ABC by symbol placement, row and column uniqueness, empty cells, outside visibility clues, and the logic each puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Calcudoku: Candidate Logic and Arithmetic Cages Compared

Compare Sudoku vs Calcudoku by row and column uniqueness, arithmetic cages, candidate sets, and the different reasoning each number puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Str8ts: Sets, Straights, and Candidate Logic Compared

Compare Sudoku vs Str8ts by row and column uniqueness, compartments, consecutive ranges, black cells, and the candidate reasoning both puzzles reward.

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Puzzle comparison7 min read

Sudoku vs Heyawake: Grid Logic and Room Shading Compared

Compare Sudoku vs Heyawake by candidate placement, numbered rooms, black-cell spacing, white connectivity, and the solving habits that carry between them.

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Puzzle comparison7 min read

Sudoku vs Tapa: Symbol Placement and Shading Logic Compared

Compare Sudoku vs Tapa by candidate sets, numbered neighbor clues, wall connectivity, 2x2 restrictions, and the visual reasoning each puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Yajilin: Candidate Logic, Shading, and Loops Compared

Compare Sudoku vs Yajilin by candidate logic, arrow clues, shading, loop construction, global connectivity, and the solving habits each puzzle rewards.

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Puzzle comparison7 min read

Sudoku vs Battleships: Placement Logic and Fleet Logic Compared

Compare Sudoku vs Battleships by candidate placement, row and column counts, ship geometry, water marking, and the spatial deductions each puzzle rewards.

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