How to play Shape Sudoku

Fill the grid so every row, column and box has each shape exactly once. Also known as Picture sudoku.

The rules

Every row contains each shape exactly once.
Every column contains each shape exactly once.
Every outlined box contains each shape exactly once.
Some shapes are given. The answer is unique.

Playing Shape Sudoku on Puzzle Solvers

Choose a 4×4 or 6×6 grid and a difficulty, then press New Puzzle.
Every row, every column and every outlined box must contain each shape exactly once.
Tap a square, then tap a shape on the pad (or type its number).
Hint shows the next square you can be sure of and why.

A worked example

The top-left square’s row already has a circle and a square, and its box has a triangle. In a 4×4 grid with circle, triangle, square and star, the only shape left for it is the star.

Now the star is in the top-left box, so no other square in that box can be a star.

Strategies

Only shape left. Look at a square: list the shapes already in its row, column and box. If only one shape is missing from that list, it goes there.
Only place left. Pick a shape and a box (or row). If the shape can only go in one square there, put it in.
Fill the fullest first. Rows, columns and boxes that are nearly full give quick answers.
Check all three. Before placing a shape, check its row, column and box.

Common mistakes

Checking only the row and forgetting the box.
Guessing — every Shape Sudoku can be solved by looking, without guessing.

Where it comes from

Picture and shape sudokus are a popular way to introduce the classic number puzzle to young children and beginners.

Frequently asked questions

How many shapes are there?

Four in a 4×4 grid and six in a 6×6 grid.

Can I type instead of tapping?

Yes — keys 1 to 6 pick the shapes in the order shown on the pad.

Is there always one answer?

Yes — every puzzle is checked to have exactly one answer.

Keep going

All guides: How to play every puzzle and game.