Sudoku 9x9

Sudoku 9x9 is the puzzle as most people first met it: a grid of nine rows and nine columns, split into nine small squares. Some cells start with a number already in them. Your task is to fill the rest so that the digits 1 to 9 each appear once in every row, once in every column and once in every small square.

Three difficulty levels are offered, easy, medium and hard, and the developer explains what separates them. The harder the setting, the fewer numbers are filled in when the puzzle begins, which leaves more of the grid for you to work out and fewer fixed points to reason from.

Hints are available during a game for when you get stuck. The developer does not list any controls for entering numbers, and the game sits in a landscape frame.

Choose easy, medium or hard. Look at the numbers already placed, then fill each empty cell with a digit from 1 to 9. No digit may repeat within a row, a column or a small square. When you cannot see the next move, ask for a hint. The puzzle is solved when every cell holds a number and none of the three rules is broken.

The developer does not list the controls for this game. It runs inside the frame above, so a click or a tap on the game is the place to start.

Every row, column and small square needs all nine digits, so a unit with eight numbers filled tells you its last one outright. Find those first. On hard, with fewer starting numbers, test each candidate against its row, column and square together before writing it in. Save hints for when no cell can be pinned down.

Classic 9x9 sudoku with three difficulty levels and hints, in a landscape frame. The difficulty setting decides how many numbers are given at the start. No controls are listed by the developer.

Sudoku Vault adds 4x4 and 6x6 boards and a Check button that locks correct digits. Sudoku for bro is also a 9x9, with a mistake check and an option to show the full solution.