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Drag to draw a rectangle • Tap a rectangle to clear it • ✔ Check is free • 💡 3 hints per puzzle
Shikaku turns one simple rule into a deep logic workout. The grid holds printed numbers. You split the whole grid into rectangles, and every rectangle must hold exactly one number and cover exactly that many cells. A rectangle around a 6 covers 6 cells. A rectangle around a 12 covers 12 cells. No guessing is ever needed. Every puzzle here has exactly one solution, and this page gives you 40 set puzzles in four sizes plus a fresh Daily Shikaku every day.
New to the game? Start on the 6×6 Starter tier. The first puzzles teach you the whole idea in a few minutes. Then climb to 7×7, 8×8 and the full 10×10 Expert grid.
🧩 Logic📅 Daily Puzzle🆓 Free📱 Mobile Friendly▦ 6×6 to 10×10
▦ The One Rule
Split the grid into rectangles. Each rectangle holds one number and covers exactly that many cells.
🔢 The Number Is the Area
A 6 can be 1×6, 2×3, 3×2 or 6×1. A prime like 7 can only be a straight line. Shape is your choice.
⭐ One Solution
40 set puzzles plus a Daily. Two independent solvers prove each one has exactly one solution before it reaches you.
✔ Check and Hints
A free Check button counts wrong rectangles, and 3 hints per puzzle place one for you. Clean solves earn 3 stars.
In this guide
- How to play Shikaku
- The one rule: the number is the area
- The sizes on GameOLL
- Solving strategies that actually work
- The Daily Shikaku and your streak
- Stars, Check and hints
- 7 tips for faster solves
- Frequently asked questions
How to play Shikaku
Press on any cell and drag across the grid. A preview follows your finger or mouse. Release, and the rectangle is placed if it follows the rule. Placed rectangles get their own colour, so the split is easy to read. Tap a placed rectangle to clear it and draw it again.
The game checks every rectangle as you draw it. A rectangle with no number inside is refused. A rectangle with two numbers is refused. A rectangle whose cell count does not match its number is refused too, and the message always says why. So a slip can never quietly break the grid. You only have to think.
| Step | What to do |
|---|---|
| 1 | Pick a puzzle, or tap 📅 Daily for today's grid. |
| 2 | Press on a cell and drag to draw a rectangle around one number. |
| 3 | Make the rectangle cover exactly as many cells as its number says. |
| 4 | Keep exactly one number inside every rectangle, and never overlap. |
| 5 | Use ✔ Check to test your work, and 💡 Hint when stuck. |
| 6 | Cover the last cell correctly and the puzzle completes. |
The one rule: the number is the area
Area is just width times height. A rectangle for the number 6 has area 6, so its sides can be 1 and 6, or 2 and 3, in either direction. Four shapes are possible: 1×6, 6×1, 2×3 and 3×2. The number can sit anywhere inside its rectangle, not just in a corner. That freedom is what makes Shikaku interesting: the number tells you the size, and the grid tells you the shape.
Prime numbers are the strictest clues on the board. A 7 cannot split into whole sides except 1×7 or 7×1, so its rectangle is always one straight line of 7 cells. The same holds for 2, 3, 5, 11 and 13. When you see a prime, you only choose its direction and where along the line it starts. Big numbers near an edge are nearly as strict: a 12 in a corner cannot reach far, so only a few of its shapes still fit.
The sizes on GameOLL
| Tier | Grid | Rectangles | Best for |
|---|---|---|---|
| Starter | 6×6 | 6 to 11 | Learning the rule |
| Classic | 7×7 | 7 to 13 | A daily warm-up |
| Tough | 8×8 | 8 to 15 | A real workout |
| Expert | 10×10 | 11 to 20 | The full test |
| Daily | 8×8 | 8 to 15 | One fresh puzzle a day |
Each tier holds 10 set puzzles, so the full set is 40 puzzles and 120 stars. The Daily is a new 8×8 puzzle every day. It pays streak days instead of stars, and it is the same puzzle for every player on that day.
Solving strategies that actually work
Start at the edges. A number on the border has lost half of its possible shapes already, because its rectangle cannot leave the grid. Corners are stricter still. Work the border numbers first and the middle of the board gets easier with every placement.
Factor every number before you draw. Reading a 12 as 1×12, 2×6 or 3×4 turns a vague clue into three concrete shapes. Then ask which shapes fit the space around it. Often only one shape survives, because the others would swallow a second number or run off the grid.
Watch for orphan cells. If a small patch of empty cells is cut off from every number that could reach it, something you already placed is wrong. A rectangle can only grow in straight lines, so any empty cell must still have a clear rectangle path to its number. Checking this one idea fixes most stuck boards.
Finish forced rectangles last if you like, but notice them early. When a number has only one legal shape left, that shape is certain, even if you draw it later. Certain rectangles shrink the board for everything else, so most solvers draw them the moment they spot them.
The Daily Shikaku and your streak
Every day, a fresh 8×8 Shikaku is generated from the date itself, right on your device. Everyone who plays that day gets the same puzzle. Solve it and your streak grows by a day. Miss a day and the streak starts again. Your streak, your stars and your best times are stored in your browser, and an unfinished puzzle is restored exactly where you left it when you come back.
Stars, Check and hints
Each set puzzle pays up to 3 stars. Finish with no hints used and no wrong Check results and you earn all 3. Use one hint, or get one wrong Check, and you can still earn 2. Anything more still earns 1 star for the solve. Check is free and unlimited: it tells you how many of your placed rectangles are wrong, but never which ones. Hints are limited to 3 per puzzle, and a hint places one fully correct rectangle for you, clearing anything wrong that stood in its way.
7 tips for faster solves
- Begin with primes: 2, 3, 5, 7, 11 and 13 are always straight lines.
- Work from the corners inward, where shapes are most limited.
- Say the factors out loud: a 12 is 2×6 or 3×4 before it is anything else.
- Count the empty cells in a region; the numbers inside it must add up to that count.
- If a cell can only be reached by one number, that number owns it.
- Stuck? Press Check before you spend a hint. It is free.
- Climb one size at a time: 6×6 teaches shapes, 10×10 tests everything.
Frequently asked questions
What is Shikaku?
Shikaku is a Japanese logic puzzle played on a square grid with numbers printed in some cells. You split the grid into rectangles so every rectangle holds exactly one number and covers exactly that many cells.
How do I draw a rectangle?
Press on a cell and drag across the grid, then release. The rectangle is placed if it holds exactly one number and covers exactly that many cells. Tap any placed rectangle to clear it and draw it again.
Can a rectangle hold two numbers, or none?
No. Every rectangle must hold exactly one printed number. A rectangle with no number, or with two numbers, is refused with a message that explains why.
Does every puzzle have exactly one solution?
Yes. Every puzzle on this page, set and Daily alike, was generated and then proven by two independent solvers to have exactly one solution. If every cell is covered by a valid rectangle, you have found it.
How does the Daily Shikaku work?
A new 8×8 puzzle is generated from the date every day, the same for every player. Solve it to build your daily streak. Your streak, stars and best times are saved in your browser.
Can I play Shikaku on my phone?
Yes. The game runs in your browser with no download and no sign-up. Drag with your finger to draw rectangles, and tap a rectangle to clear it. The grids are sized to fit your screen, even the 10×10 Expert boards.
🏆 Final Verdict
Shikaku is the purest shape-logic workout on GameOLL. One rule, zero luck, and every puzzle proven to have exactly one answer. Start with the 6×6 tier, earn your stars, keep the Daily streak alive, and take on the 10×10 Expert boards when the rectangles start solving themselves in your head.
A note on the name: Shikaku is the Japanese rectangle-division puzzle style popularised by Nikoli. This page is an independent GameOLL implementation. Every grid, rectangle layout and line of code here is original to GameOLL, and the puzzle format itself is a classic logic format anyone may implement.
Last updated: November 8, 2026
