Sudoku 43

How to play one grid, one logic

Sudoku is pure deduction, no arithmetic. Fill the nine by nine grid so that every row, every column and every three by three box holds the digits one to nine exactly once. The numbers given at the start never move, and from them the rest of the grid follows by elimination alone.

Where beginners get stuck

The instinct is to stare at an empty cell and ask what could go here. The faster habit is the opposite: pick a digit, and ask where it is forced to go in a box. Scan row by row, cross off the columns and rows that already hold that digit, and often a single square is left. That is a placement no guessing required.

Notes are not cheating

On medium and up, pencil marks are how the puzzle is actually solved. Turn on Notes, fill each empty cell with its candidates, and watch pairs appear. Two cells in a box that can only be a four or a seven lock those two digits out of every other cell they share, and the grid starts to open.

Five levels, every day

Everyone playing on Thursday, February 12, 2026 gets the same five grids, one at each level, swapped at midnight UTC. Easy is a clean warm up. Evil will test the hardest chains you know. Your time and your streak stay in this browser, with no account and nothing to sign.