Medium Sukaku

A digit-free variant — only pencil marks are given, not final answers. Solve from candidate sets rather than placed digits.

Easy Medium Hard Expert

Sukaku at medium difficulty. Naked pairs and hidden singles become essential as initial easy eliminations run out.

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Mistakes
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Score
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Time
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Tap a number to eliminate it from selected cell
Try Hard Sukaku →
Progress0%

What is Sukaku?

Difficulty
★★★☆☆
3/5
Constraint Type
Pencilmark Elimination
Typical Givens
All candidates shown
Avg. Solve (Medium)
18 min

Solving Techniques for Medium Level

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

Master these, then take on Hard Sukaku to learn Advanced techniques.

Techniques to Master at Medium

  • Hidden Singles technique — With every candidate printed, hidden singles become countable: tally a digit's appearances across each unit's pencilmarks, and a count of one is an immediate placement.
  • Obvious Pairs technique — The given pencilmarks expose pairs that classic solvers must derive — two cells printed with the same two candidates are a pair from the very first glance.

Average Solve Time by Difficulty

Easy
8 min
Medium
18 min
Hard
35 min
Expert
62 min
Want a full walkthrough of rules, strategies, and solving steps? How to Play Sukaku →

Related Variants

Killer Sudoku

Another puzzle that opens with zero placed digits — cage sums replace pencilmarks as your only raw material.

Jigsaw Sudoku

Sharpens the same candidate-tracking discipline sukaku trains, with region shapes that twist your eliminations.

Diagonal Sudoku

Adds two more houses to feed your elimination engine — ideal for solvers who enjoy sukaku's systematic pruning.

Frequently Asked Questions — Medium Sukaku

What strategies work for medium Sukaku?
Medium Sukaku responds well to naked singles (a cell with one candidate left), hidden singles (a digit that appears as a candidate in only one cell within a row, column, or box), and naked pairs (two cells in a unit that share the same two candidates, letting you remove those digits from all other cells in the unit).
How does elimination work across rows, columns, and boxes in Sukaku?
When you eliminate a candidate from a cell and only one remains, that digit is confirmed. You must then remove it as a candidate from every other cell in the same row, the same column, and the same 3x3 box. Each elimination triggers a chain of further removals — this cascade is the core mechanism of Sukaku solving.
What is a hidden single in Sukaku?
A hidden single occurs when a digit appears as a candidate in only one cell within a row, column, or box, even though that cell still shows multiple candidates. Because the digit must go somewhere in the unit, the cell containing it as the only option must take it. Eliminating the other candidates from that cell confirms the placement.
Why does medium Sukaku take longer than easy?
Medium puzzles start with fewer candidates pre-eliminated in the initial state, meaning fewer obvious cells. You need to apply multiple elimination techniques before progress unlocks, rather than scanning for immediate singles. The cascade of deductions is longer and requires tracking several units at once.
Can I make mistakes in Sukaku by eliminating a correct candidate?
Yes. If you eliminate a digit that is actually the correct answer for a cell, the puzzle becomes unsolvable in that region. Always use logical deduction rather than guessing. If you feel stuck, check whether any unit (row, column, box) would be left with no valid cell for a particular digit after your proposed elimination.

More questions? See the full Sukaku guide.