In short. Put your finger on a square and drag to the opposite corner to draw a rectangle. Each rectangle must hold exactly one number and cover as many squares as that number; together they fill the whole grid without overlapping. Tap a tile to lift it. Once the grid is done, “Next grid” serves another.
Below the grid, pick the size, from 5 × 5 to 20 × 20, and the difficulty. A 10 × 10 fits in a coffee break; a 15 × 15 or a 20 × 20 is more comfortable on a computer, where the squares are bigger.
Shikaku rules in thirty seconds
- One number per rectangle, no more, no less.
- The number is the area: a 6 can be 1 × 6, 2 × 3, 3 × 2 or 6 × 1.
- The whole grid is covered, with no gaps and no overlaps.
While you drag, a bubble above your finger counts the squares: “4 / 6”, two to go. The four deductions that solve every grid are explained in the Shikaku rules.
Grids made on demand
Every grid comes out of the engine of our game Mosaic. It cuts the grid into random rectangles, chunky rather than skinny, hides a number in each one, then replays the grid with its four deductions. If they cannot finish it, the grid is thrown away: the one you get has exactly one solution and never needs a guess. It all takes a few milliseconds, which is why there is no waiting.
Choosing size and difficulty
Here, difficulty is not measured by size but by the hardest deduction you will need:
- Easy: a number with only one place left, a square only one rectangle can still cover. You place a tile almost every move.
- Medium: you have to spot the square only one number can reach, and conclude that its rectangle must pass through it.
- Tough: a number that, whatever its shape, always covers the same square, which rules that square out for everyone else. This reasoning often happens far from the number.
A small tough grid gives you more trouble than a big easy one. Your settings are kept for your next visit, along with the number of grids you have solved here.
Shikaku of the day
“Shikaku of the day” serves the same 10 × 10 grid to everyone, and a new one every day at midnight. Once it is done, “Share my time” sends your time to a friend, with a link to the same grid.
Stuck? A hint that explains
The “Hint” button places nothing for you: it outlines the next forced rectangle and says why, in one sentence. Placing it is up to you. If a tile is wrong, it shows it in red first. At the end, the message notes how many hints you took.
Fancy grids that draw a heart, a house or a fish? The game Mosaic has a hundred and seventy levels, silhouettes included, with the same hint that explains.
Frequently asked questions
Can I play Shikaku online for free?
Yes: no account, no ads on this page, on a phone or a computer. The grids are unlimited.
Is there a Shikaku of the day?
Yes. “Shikaku of the day” serves the same 10 × 10 grid to everyone, and changes it every day at midnight.
Do the grids have a single solution?
Always. Every grid is replayed by deduction before it reaches you: if deduction cannot finish it, the grid is thrown away. A grid that solves without a guess has only one solution.
Do I ever have to guess?
Never here. Every rectangle follows from the numbers and the rectangles already placed.
Which size should I pick?
A 5 × 5 to learn the gesture, a 10 × 10 for a break, a 15 × 15 for a proper game. The 20 × 20 plays better on a computer.
Shikaku, Rectangles, Divide by Box: same game?
Yes. Shikaku is the name given by Nikoli, the Japanese publisher that brought it out; you will also find it as Rectangles, Divide by Box or Cell Block.
If you like this one
One line puzzlesFill · Play now
Pipe puzzlesRoll · Play now