Medium Chaos Construction Sudoku

Irregular region boundaries are deduced during the solve. The grid's own logic reveals where the boxes lie.

Easy Medium Hard Expert

Chaos Construction Sudoku at medium difficulty. Map every region boundary first, then apply row, column, and region eliminations together.

3
9
4
4
8
7
1
8
5
9
7
1
8
2
1
4
8
2
9
3
6
5
7
2
1
4
2
1
6
5
2
3
Thick borders separate different regions. Deduce the 9 regions as you solve.
Mistakes
0/3
Score
-
Time
00:00
Try Hard Chaos Construction →
Progress0%

What is Chaos Construction?

Difficulty
★★★★☆
4/5
Constraint Type
Hidden Irregular Regions
Typical Givens
24–32
Avg. Solve (Medium)
26 min

Solving Techniques for Medium Level

Technique Description Level
Border Reading Thick borders separate cells in different regions. Cells without thick borders between them are in the same region. Map connected groups first. Beginner
Region Size Counting Each region contains exactly 9 cells. Count connected groups to verify region membership and identify boundaries. Intermediate
Deducing Regions from Digits If standard row/column logic places a digit, use that placement to confirm or deny region membership — a region can only contain each digit once. Intermediate

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

Techniques to Master at Medium

  • Hidden Singles technique — Every hidden single found by line logic does double duty: the placement also tests region hypotheses, since a deduced region may not repeat the digit you just placed.
  • Obvious Pairs technique — Once a partial region is confirmed, pairs inside it eliminate like box pairs — and a pair that would force a repeat inside a candidate region disproves that region shape.

Average Solve Time by Difficulty

Easy
12 min
Medium
26 min
Hard
50 min
Expert
80 min
Want a full walkthrough of rules, strategies, and solving steps? How to Play Chaos Construction →

Related Variants

Jigsaw Sudoku

The visible-region version of what you solve here — practise pure jigsaw logic without the border deduction.

Samurai Sudoku

Another heavyweight: less meta-deduction, more scale, with five grids trading information through shared boxes.

Clone Sudoku

Also about grid structure carrying information — twin regions that must hold identical digit layouts.

Frequently Asked Questions — Medium Chaos Construction Sudoku

What techniques do I need for medium Chaos Construction?
Medium puzzles require you to fully map every region boundary before solving begins. Once you know the regions, apply standard elimination — naked singles, hidden singles — using three constraints at once: rows, columns, and irregular regions simultaneously.
How do I figure out the region boundaries in Chaos Construction?
Start at a corner or edge cell and trace every thick border it borders. Each connected group of cells inside thick borders is a single region. It helps to lightly shade or label regions in pencil before you start placing digits.
Can the same digit appear in the same region twice in Chaos Construction?
No. Each of the nine irregular regions must contain every digit from 1 to 9 exactly once, just like rows and columns. If a digit is already placed in a region, it cannot appear anywhere else in that region.
Why are medium Chaos Construction puzzles harder than medium regular Sudoku?
In regular Sudoku the box boundaries are obvious. In Chaos Construction you must first deduce and memorize irregular shapes, then apply three-way constraints — rows, columns, and irregular regions — simultaneously. The mental overhead is significantly higher.
How long does a medium Chaos Construction puzzle take to solve?
Most players finish a medium Chaos Construction puzzle in 15–30 minutes. If you're new to the variant, budget extra time for tracing region boundaries before the actual solve begins.

More questions? See the full Chaos Construction Sudoku guide.