Rules
- Each row has exactly one cat.
- Each column has exactly one cat.
- Each area, outlined by thick lines, has exactly one cat.
- Cats may not touch, not even diagonally.
Every puzzle has exactly one answer and can be solved by logic alone, without guessing. Which cat appears is purely cosmetic and never affects the rules.
Reading the board
- Empty: not decided yet
- Cross: your note that no cat is here
- Cat: a cat sits here
- Hatching, a red ring, and a worried face: a cat that breaks a rule
Controls
With large cells, each tap cycles a cell: empty → cross → cat → empty. With small cells, Select then act turns on: tap a cell to select it, then use the large buttons below the board for cross, cat, or clear. Tapping the selected cell again also cycles it. You can change the controls below the board at any time.
Turn on the Cross pen switch right under the board (off by default) to swipe across the board and cross every empty cell you pass. Cats and crosses stay as they are, the crosses appear when you lift your finger, and one Undo takes the whole swipe back. Taps work as before. While the pen is on, the page does not scroll on the board, so scroll outside it.
Keyboard controls
- Arrow keys
- Move between cells
- Space / Enter
- Cycle empty → cross → cat (in Select then act, cycles the selected cell)
- X / C
- Toggle a cross / toggle a cat
- Delete
- Clear the cell
- U / Ctrl+Z
- Undo one move
- Home / End
- Jump to the start or end of the row
- H
- Hint (press again to show the cells)
Daily and Practice
Daily gives one puzzle per day for each board size (6×6, 7×7, 8×8), based on your device's date. Everyone gets the same puzzle for the same date and size, and solving it that day records it once. When the date changes a new puzzle takes over, and finishing the previous day's puzzle no longer counts. Puzzles are built from the date, so occasionally two dates may share the same board.
Practice lets you play as many puzzles as you like in any size. It never affects Daily records or your streak, and only adds to your total. Boards in progress are saved, so you can come back to the same puzzle later. Practice also offers 8×8 Expert, which needs a harder kind of reasoning, and 9×9 Master, which needs that reasoning again and again on a bigger board. Neither is ever a Daily.
Hints and the cat collection
A hint first tells you which row, column, or area to look at and why. Choose Show me where to highlight the cells for a cat or a cross. Hints never change the board by themselves. If a cat or cross is wrong, the hint points that out first. Hints you use are counted, but they never add to your solved records.
The cat collection has four cats: Shiro, Kuro, Chatora, and Mike. You meet a puzzle's guide cat the first time that puzzle is recorded as solved. Solving the same puzzle again does not count as meeting the cat again.
Saving your records
Daily clears, your streak, practice records, boards in progress, the cat collection, hint counts, and control settings are saved only in this browser's localStorage (picochest.cat-logic.v1). They are not sent to a PicoChest server and do not carry over to other devices or browsers. Clearing your browser data removes them. See the Privacy Policy for details.