Candidate marks that keep your reasoning clear

A blank cell is a possibility

A blank cell is a possible cat location until a rule excludes it. An × is your note that the location is unavailable. It does not change the puzzle rule or certify that your deduction was correct. Leaving a cell unmarked is safer than crossing it out because it merely looks unlikely.

After placing a cat, review its row, column and region, then its eight immediate neighbors. Each exclusion should have one of those reasons. In the example below, follow the first explained placement and compare its affected cells with your own notes.

Switch tools before you act

Place cat and Mark × are separate modes. Both work with one tap or click; right-clicking and double-tapping are not required. On a keyboard, arrows move focus, Space uses the selected tool, and X toggles a note directly. The visible focus border tells you which cell will change.

Notes are saved with the current game and participate in Undo and Redo. Undoing an exclusion is a normal correction, not a penalty. The game does not award a benefit for adding as many × marks as possible.

Do not turn a note into an assumption

If you cross out a true candidate accidentally, the board may appear to have no place for a cat. Recheck the reason for the most recent notes before guessing. GridMew’s logical hint engine derives steps from rules and cats rather than treating all your notes as proven facts.

In the custom solver, × notes are ignored by default. Turn on Treat × notes as exclusions only if you deliberately want to solve under those assumptions. A no-solution result then may be caused by a note rather than by the original regions.

A real step from gm-5-0001