## Sudoku Uno Family of Apps

Enjoy endless Sudoku fun. Sudoku Uno can create a seemingly unlimited number of Sudoku grids for you to solve. Sudoku Duo on iPad allows you to partner up with a second player or challenge an opponent to solve a Sudoku grid while both of you use the same iPad.

The Sudoku Uno apps know how to solve Sudoku puzzles. They apply the same techniques you would use. This gives Sudoku Uno the unique ability to explain the reasoning behind the hints it gives you. The hints thus will not only help you win the game, but will also help you improve your skills.Since Sudoku Uno knows what techniques are needed to solve a given grid, it can assess the skill level needed. You get to chose between three levels of difficulty: easy, medium & hard.

- Difficulty levels are determined by techniques to master, not by number of givens
- Unlimited number of Sudoku games
- Green & red pencil notes
- Optional automatic pencil notes
- Intelligent hints with explanations
- High scores

## Free Software

The Sudoku Uno and Duo apps are available for free from the Apple App Stores. There are no ads or in-app purchases. No strings attached.

If you love Sudoku Uno, please leave a review and check out our other products.

## Game of Sudoku

A Sudoku board is grid of 9 × 9 cells. These are grouped into 9 blocks of 3 × 3 cells.

The goal of the game is to fill the cells of the grid with the digits 1 through 9 so that:

- Each row contains each digit exactly once
- Each column contains each digit exactly once
- Each block contains each digit exactly once

Sudoku games start with a partially filled grid. Your task is to fill in the remaining cells. This should be done by deduction only. A well-formed Sudoku has only one solution and that can be found by logic reasoning.

## Sudoku Solving Techniques

At the core of Sudoku Uno is a Sudoku solver that relies solely on “human logic”. It solves Sudoku boards by applying the same techniques you would use. Sudoku Uno can thus be sure that a board can be solved. Knowing which techniques are needed in the process, it can also assess the difficulty level of the game. What’s more, Sudoku Uno can offer helpful hints when you get stuck: it will tell you which technique to apply and which steps to take.

### Easy: Single Candidate

When for a given cell all but one candidates have been ruled out, the candidate value should be written to the cell.

### Easy: Single Position in Row

When in a given row a given digit is candidate to only a single position, the candidate value should be written to the cell.

### Easy: Single Position in Column

When in a given column a given digit is candidate to only a single position, the candidate value should be written to the cell.

### Easy: Single Position in Block

When in a given block a given digit is candidate to only a single position, the candidate value should be written to the cell.

### Easy: Conjugate Pairs

When 2 cells in a given group (row, column or block) have only 2 candidates, and when those candidates are identical for both cells, those digits can be eliminated as candidates from all other cells in the group.

### Medium: Pointing Pairs in Row

When within a given block a digit can only occur in one row, that digit may be eliminated as candidate elsewhere in that row.

### Medium: Pointing Pairs in Column

When within a given block a digit can only occur in one column, that digit may be eliminated as candidate elsewhere in that column.

### Medium: Block Reduction in Row

When in a given row all candidate positions for a given digit are within the same block, the digit may be eliminated as candidate to any other cell in that block. This technique eliminates the same candidates as "Pointing Pairs in Row."

### Medium: Block Reduction in Column

When in a given column all candidate positions for a given digit are within the same block, the digit may be eliminated as candidate to any other cell in that block. This technique eliminates the same candidates as "Pointing Pairs in Column."

### Hard: Hidden Pair in Row

When two digits are candidates to exactly two cells within a given row, all other candidates may be eliminated from these cells.

### Hard: Hidden Pair in Column

When two digits are candidates to exactly two cells within a given column, all other candidates may be eliminated from these cells.

### Hard: Hidden Pair in Block

When two digits are candidates to exactly two cells within a given block, all other candidates may be eliminated from these cells.

### Hard: X-Wing in Row

When a digit is candidate to two cells in two rows and both candidates share the same column, all other instances of that candidate may be eliminated from the two columns.

### Hard: X-Wing in Column

When a digit is candidate to two cells in two columns and both candidates share the same row, all other instances of that candidate may be eliminated from the two rows.

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