Shikaku Puzzle

Shikaku is a calm logic puzzle about rectangles. Divide the whole grid so that every rectangle contains exactly one number — and that number tells you how many squares the rectangle covers.

How to play Shikaku Puzzle

• Divide the grid into rectangles (squares count too) so that every square belongs to exactly one rectangle.
• Each rectangle must contain exactly one number, and that number is its area: a 6 could be 1×6, 2×3, 3×2 or 6×1.
• Drag from one corner to the opposite corner to draw a rectangle. Drawing over existing rectangles replaces them. Tap a rectangle to remove it.
• Correct rectangles fill with colour; dashed red ones have the wrong area or the wrong number of clues inside.
• Every puzzle is generated by our own code and has exactly one solution, reachable by logic.

Controls

• Drag: draw a rectangle   Tap: remove one
• Arrow keys move, Space / Enter marks one corner then the other, Delete removes, Z undo, H hint

Tips

• Start with numbers that can only fit one way, such as a large number squeezed into a corner, or a prime number next to the edge.
• Look at squares far from any clue: work out which numbers could possibly reach them.
• A 2 or 3 tucked between other clues often has only one direction it can stretch.
• If a rectangle could be drawn several ways, leave it for later; other rectangles will rule options out.

FAQ

What are the rules of Shikaku?

Divide the grid into rectangles so that each one contains exactly one number, and the number equals the rectangle’s area in squares. Every square must be used, and rectangles cannot overlap.

How do you solve a Shikaku puzzle?

Find clues with only one possible rectangle first — large numbers near walls, or primes like 5 and 7 that can only be a single strip. Each placed rectangle blocks space for its neighbours, which forces the next ones.

What does Shikaku mean?

Shikaku is Japanese for “square” or “four corners”. The puzzle is also known as Divide by Squares or simply the rectangles puzzle.

Does every Shikaku here have one solution?

Yes. Our generator cuts a grid into random rectangles, places one number in each, and keeps the puzzle only if a solver confirms there is exactly one solution.