GridMewCorrect a mistake without losing the puzzle
Distinguish a direct conflict, a wrong guess and an incorrect × note.
On this page
Direct conflicts explain what changedRecheck notes before moving catsUse recovery controls deliberatelyApply the ideaOriginal exampleCheck your understandingOriginal GridMew lesson · Updated 16 October 2026
Learning goal: Diagnose whether a contradiction comes from a cat, a note or a misread input before restarting.
Direct conflicts explain what changed
Two cats in one row, column or region violate a quota. Two cats touching at a corner violate adjacency. GridMew highlights involved cells and names the immediate problem. Undo the latest move or remove the cat you meant to change; you do not need to restart the whole puzzle.
A placement can be wrong even when it has no immediate conflict. It might rule out every valid completion several steps later. Before building more reasoning on top of a guess, ask whether the placement was actually forced.
Recheck notes before moving cats
If a row seems to have no candidate, inspect the × notes that excluded it. A mistaken note can make a valid board look impossible. Clear or undo the unsupported note rather than forcing a cat into a ruled-out position.
Game hints use rules and placed cats. Custom solver notes become assumptions only when Treat × notes as exclusions is selected. Running the custom solver both with and without notes can help identify which kind of input caused a contradiction.
Use recovery controls deliberately
Undo reverses an ordinary board operation; Redo restores it. Restart clears the current cats and notes after confirmation, while keeping your completed record. Fixed cats remain part of the original puzzle.
Browser storage is local. Export a backup before clearing records or browser data. Import checks format and puzzle IDs before merging; an incompatible file should leave your current progress untouched. See My progress for those controls.
Apply the idea to gm-6-0005
r2c3 means row 2, column 3, counting from the top left.
In gm-6-0005, the original givens allow a unique solution. The route places r6c6, then r3c1. If you accidentally mark r3c1 as excluded, the original board has not changed: your note has contradicted its only completion.
For a custom board, solve first with notes ignored. If that succeeds but using notes yields no solution, review those assumptions. If both fail, compare regions and fixed cats with the original input. A time-limited “Search not finished” result belongs to neither category; it is not evidence that your board is impossible.
A real step from gm-6-0005
row 3 has only one remaining candidate: row 3, column 1. Every other cell is excluded by earlier placements or deductions. Place the cat here.
Check your understanding
Does a no-solution result with an × at r3c1 prove the published gm-6-0005 puzzle is broken?
Show the explanation
No. That note excludes a required cat in the original unique solution. Remove or undo the unsupported note, then check the unchanged regions and fixed cats. The distinction can be tested with notes included and ignored in the custom solver.