How to play Shikaku
Cut the grid into rectangles so that every rectangle holds exactly one number, and that number is its area in cells.
The rules
- Every cell must end up inside a rectangle, and rectangles cannot overlap.
- Each rectangle contains exactly one number.
- That number equals the rectangle's width times its height. A 6 can be 1x6, 2x3, 3x2 or 6x1, as long as it fits.
- Squares count as rectangles. A 4 can be a 2x2 block.
The puzzle ends the moment the whole grid is correctly divided. There is no button to press.
Controls
- Draw: press on a cell and drag to the opposite corner. While you drag, the outline shows the current area, and it turns solid red when the shape satisfies the rules.
- Remove: tap or click a rectangle.
- Replace: draw a new rectangle over old ones and any it overlaps are removed.
- A 1: tap the number and its single cell is placed straight away.
You may draw a rectangle that breaks the rules. It stays on the board as a dashed, hatched shape until you change it, which is handy for thinking out loud. Drawing needs a mouse, finger or stylus; there is no keyboard control for the board.
Buttons
- Undo steps back one action at a time, including a Clear.
- Clear removes every rectangle but leaves the clock running.
- Hint places one correct rectangle for you, starting with the smallest missing piece and favoring spots where you have gone wrong. Anything it overlaps is removed.
- Check marks each rectangle that differs from the solution and tells you how many cells are still uncovered. Checks are not counted against you.
Daily and Practice
Daily is one 10x10 puzzle per calendar date, changing at midnight on your device. Practice gives you fresh puzzles at 5x5, 7x7, 10x10 or 15x15. Each practice size keeps its own unfinished board, and New puzzle throws the current one away.
Time, streaks and best times
There are no points. The game records your time, and the clock pauses while the tab is hidden. Your daily streak grows by one for each day in a row you solve the Daily, and it ends if you miss a day. Best times are kept per board size. A solve that used a hint still counts toward your streak, but it can never set a best time. When you finish, you can share a short summary with your time, hint count and streak.
Strategy
- Start with the fussy numbers. A 7 or 11 can only be one cell wide, so near a wall or among other numbers it often has a single legal placement. A 12 can be 2x6 or 3x4, and 1x12 will not fit on a 10x10.
- Look at the corners. A corner cell has to belong to something. Often only one number can reach it, and that decides the number's shape.
- Hunt for lonely blank cells. Pick a blank cell walled in by finished rectangles and ask which numbers could possibly stretch to it. If there is only one, part of that rectangle is settled.
- Remember the one-number rule. A shape that would swallow a second number is out, so neighboring numbers cut down each other's options quickly.
- Keep leftovers honest. If a move leaves a pocket of cells no number can fill exactly, that move is wrong.
Questions
Does each puzzle have only one solution?
Yes. The generator confirms a single solution before a puzzle is used, so you never need to guess between two valid layouts.
Why did Check mark a rectangle that looks right?
Check compares against the solution. A rectangle can hold the right number and have the right area, yet still be the wrong shape or position for this puzzle.
If I undo a hint, does it stop counting?
No. Undo removes the rectangle, but the hint stays on your tally for that puzzle.
Will I lose my board if I leave?
Today's Daily and your unfinished practice boards are saved in this browser, with their clocks, and pick up where you left off.
Can I replay a past Daily?
No. Only today's Daily is available, but Practice has as many puzzles as you want.