Hard Sukaku
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9
Mistakes
0/3
Score
-
Time
00:00
Tap a number to eliminate it from selected cell
Progress0%
Hard · Sukaku
All Sukaku →
How to play Sukaku
Every cell starts with a set of candidate digits shown as pencilmarks. Press a number to eliminate that candidate from the selected cell. When only one candidate remains, the digit is placed automatically. Cells showing a single large digit are fixed and cannot be modified. Standard Sudoku row, column, and box rules apply.
About Sukaku
Difficulty
★★★☆☆
3/5
Constraint Type
Pencilmark Elimination
Typical Givens
All candidates shown
Avg. Solve (Medium)
18 min
Sukaku (数角) is a Sudoku variant where instead of given digits, each cell is given a set of possible candidates. The solver must eliminate candidates using standard Sudoku logic until each cell has exactly one remaining candidate. Some Sukaku puzzles provide very sparse candidate sets (near-complete givens), while others provide full or nearly-full candidate lists, requiring advanced techniques to solve.
Solving Techniques
| Technique | Description | Level |
|---|---|---|
| Candidate Scanning | Start by scanning rows, columns, and boxes — any candidate appearing in only one cell in a group must be placed there. | Beginner |
| Cross-Hatch Elimination | When a digit is placed (or reduced to one candidate), eliminate it from all cells in the same row, column, and box. | Beginner |
| Naked Singles | A cell with only one remaining candidate is a naked single — the digit is forced. In Sukaku, this happens automatically when you eliminate down to one candidate. | Intermediate |
| Hidden Singles | A candidate that appears exactly once in a row, column, or box must be placed in that cell regardless of how many other candidates that cell shows. | Intermediate |
| Pair Elimination | Two cells in a group that share only the same two candidates form a naked pair — both candidates can be eliminated from all other cells in that group. | Advanced |
Average Solve Time by Difficulty
Easy
8 min
Medium
18 min
Hard
35 min
Expert
62 min