What is Shikaku?
Shikaku is a rectangle-drawing puzzle. The daily board is a ten-by-ten grid scattered with numbers. Your goal is to divide the entire grid into rectangles so that each rectangle contains exactly one number and that number equals its area in cells. Every cell must belong to exactly one rectangle. The page tracks streak, best time, and puzzles solved above the grid. A timer starts when you press START, a countdown shows when the next puzzle arrives, and the leaderboard on the right ranks finishers by completion time.
How to play Shikaku
- Press START to begin the timer.
- Drag across the grid to draw a rectangle.
- Click a single cell to place a 1.
- Right-click or click an existing rectangle to erase it.
- Continue cutting until every cell belongs to exactly one rectangle and every rectangle contains exactly one number equal to its area.
- Submit your time to the leaderboard once the grid is complete.
Why play Shikaku?
Most logic puzzles are solved by marking cells. Shikaku is solved by dividing territory. A clue is a shape looking for a place to fit, and deduction happens between rectangles that cannot both occupy the same space rather than within a single square. The site emphasizes speed with a live timer, performance counters, and a daily leaderboard ranked by finishing time.
Reading the feedback
The puzzle measures completion time rather than attempts. The three counters above the board update only after a solve, so the timer is your only live signal during play. Feedback is social rather than corrective: the leaderboard beside the board shows the day's standings ordered by time, with a share button next to reset. The entry button reads SOLVE TO SUBMIT.
Modes
Daily: One ten-by-ten board per day, the same for everyone worldwide. A countdown under the grid shows when the next puzzle arrives.
Play: A separate navigation entry offering unlimited practice puzzles.
Archive: Access to past daily puzzles through the navigation menu.
Tips and strategy
Start with clues that have only one possible shape. A prime number can only form a one-cell-wide strip, either horizontal or vertical, so its shape is determined and only its position needs solving.
Remember that every cell must be covered. An empty square surrounded by finished rectangles is not a leftover to handle later—it is proof that one of the surrounding rectangles is incorrect.
Popular questions
Can a rectangle contain two numbers?
No. Each rectangle holds exactly one clue, and that clue equals the number of cells in it (width times height).
Do I have to cover the entire grid?
Yes. Every cell belongs to exactly one rectangle. This constraint makes the areas add up and turns wrong guesses into visible contradictions.