About Shikaku
Shikaku is a Japanese logic puzzle with one elegant rule and a lot of quiet depth. You are given a grid dotted with numbers, and you divide the whole grid into rectangles so that each rectangle contains exactly one number, and that number equals the area of the rectangle. Cover the grid perfectly and the puzzle is solved.
Like the best logic puzzles, every Shikaku has a single solution you can reach by pure reasoning, with no guessing required. A number like 3 can only be a one-by-three or three-by-one block, which often pins it in place; a 7 forces a straight line of seven. Chaining these certainties together is the whole, satisfying game.
This browser version saves your progress and plays the same with a mouse or a thumb. It is calm, timer-free and genuinely brain-stretching, the sort of puzzle you finish feeling a little sharper.
How to play Shikaku
Divide the grid into rectangles so each one holds exactly one number, and that number is the area of the rectangle in squares. Every cell must belong to exactly one rectangle, and rectangles cannot overlap. Use the numbers that have only one possible shape to anchor the solution, then work outward.
| Desktop | Click and drag to draw a rectangle around cells |
|---|---|
| Mobile | Drag across cells to mark a rectangle |
| Logic | Each number equals its rectangle area |
| Goal | Cover the whole grid with valid rectangles |
Tips & strategy
- Start with numbers that have only one possible shape, such as a number that equals a full row or column length.
- A prime number like 5 or 7 must be a single straight line, which often fixes it immediately.
- Work from the edges and corners inward, where rectangles have fewer ways to fit.
- Every cell belongs to one rectangle, so an isolated empty square tells you a nearby block must reach it.
- No guessing is needed. If you are unsure, there is always a forced move somewhere else first.
Frequently asked questions
How do you play Shikaku?
Divide the grid into rectangles so each rectangle contains one number, and that number equals the area of the rectangle in squares.
Is there always a single solution?
Yes. Every Shikaku puzzle has exactly one solution you can reach by logic, with no guessing required.
Where should I start?
Begin with numbers that have only one possible shape, such as primes that must form a single straight line.
Does Shikaku save my progress?
Yes. Your progress is kept in your browser on the same device.
Is it free to play?
Yes. It runs free in your browser with no install and no account.
