Shikaku
The rule
Cut the whole grid into rectangles.
- Every number must end up inside its own rectangle.
- That rectangle must cover exactly as many cells as the number says: a 6 owns six cells, a 2 owns two.
- Rectangles fill the grid completely. No gaps, no overlaps.
That is the entire rule. Finding the one arrangement that satisfies it is the game.
A worked example
Look at the 8. In a four by four grid, eight cells can only be a two by four block, and only one such block covers its clue without stealing another number's cell. Cut it, and the board shrinks. The 4 now has exactly one two by two home, and the two 2s fall in as dominoes. That is the whole rhythm of Shikaku: each number narrows its own possibilities until exactly one shape fits.
Your moves
- Drag from one corner of a rectangle to the other to cut it.
- Tap a rectangle to erase it and try another shape.
The board answers as you play: a cut that breaks the rule shows you so immediately, and a satisfied clue settles into place.
Why you never have to guess
Every board in Kire is certified to have exactly one solution, reachable by pure logic. If you are stuck, the board is not broken and the answer is not a coin flip: there is always a next deduction waiting somewhere on the grid. Start with the biggest numbers (they have the fewest possible shapes), watch the corners and edges (they trap rectangles), and let every placed cut shrink the choices for its neighbours.
One board a day, same for everyone
Kire publishes one daily Shikaku. Everyone in the world gets the identical board, so your solve time lands in a real field: your placing, your percentile, one dot per solver. Solve it daily and your streak grows.
Go deeper in the app
The daily is the warm-up. The Kire app for Android adds the Climb: seven chapters of graded pitches rising to 12×12, seven extra deduction rules taught one at a time on real boards, the ranked daily board, and streaks on a real calendar. Never a guess in any of it.