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New Tutorial: Master Advanced Sudoku Techniques

New Tutorial: Master Advanced Sudoku Techniques

Visualize the logic of Skyscraper, 2-String Kite, and Turbot Fish (X-Chain).

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Today's Sudoku

18 March 2026

 

Sujiken

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Sujiken (from Japanese "sujikai", literally "diagonal") is a variation of Sudoku . The puzzle consists of a triangular grid of cells containing digits from 1 to 9. The objective is to fill a grid with digits so that each cell contains a digit and no digit is repeated in any column, row and diagonal in any direction. Also, no digit occurs twice in any of the three larger 3 x 3 square regions and any of the three larger triangular regions enclosed by thick borders.
Sujiken

Sujiken

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Sujiken (from Japanese "sujikai", literally "diagonal") is a variation of Sudoku . The puzzle consists of a triangular grid of cells containing digits from 1 to 9. The objective is to fill a grid with digits so that each cell contains a digit and no digit is repeated in any column, row and diagonal in any direction. Also, no digit occurs twice in any of the three larger 3 x 3 square regions and any of the three larger triangular regions enclosed by thick borders.

 

Maximin Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • A number at the edge of the diagram indicates the difference between the highest and the lowest number in the first three cells in the corresponding row or column.
Maximin Sudoku

Maximin Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • A number at the edge of the diagram indicates the difference between the highest and the lowest number in the first three cells in the corresponding row or column.

 

Skyscrapers Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Consider each number to be the height of a building. The numbers outside the grid indicate how many buildings can be seen when looking in that direction (taller buildings conceal smaller buildings behind them).
Skyscrapers Sudoku

Skyscrapers Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Consider each number to be the height of a building. The numbers outside the grid indicate how many buildings can be seen when looking in that direction (taller buildings conceal smaller buildings behind them).

 

Little killer sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Numbers with arrows indicate sum of the numbers in each direction.
Little killer sudoku

Little killer sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Numbers with arrows indicate sum of the numbers in each direction.

 

Sum Frame Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Digits outside the grid indicate the sum of the first 3 digits in the corresponding direction.
Sum Frame Sudoku

Sum Frame Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Digits outside the grid indicate the sum of the first 3 digits in the corresponding direction.

 

Greater Than Kropki Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • In all cases where two digits have a consecutive value or one digit is two times as big as the other digit (or both), a greater than sign is placed. Digits have to be placed in accordance with the sign.
Greater Than Kropki Sudoku

Greater Than Kropki Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • In all cases where two digits have a consecutive value or one digit is two times as big as the other digit (or both), a greater than sign is placed. Digits have to be placed in accordance with the sign.

 

Perfect Squares

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • A dot between two cells indicates that the digits in the two cells form a double digit square number in the reading direction. there are no square numbers marked by a dot.
Perfect Squares

Perfect Squares

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • A dot between two cells indicates that the digits in the two cells form a double digit square number in the reading direction. there are no square numbers marked by a dot.

 

Greater Than Kropki Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • In all cases where two digits have a consecutive value or one digit is two times as big as the other digit (or both), a greater than sign is placed. Digits have to be placed in accordance with the sign.
Greater Than Kropki Sudoku

Greater Than Kropki Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • In all cases where two digits have a consecutive value or one digit is two times as big as the other digit (or both), a greater than sign is placed. Digits have to be placed in accordance with the sign.

 

Skyscrapers Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Consider each number to be the height of a building. The numbers outside the grid indicate how many buildings can be seen when looking in that direction (taller buildings conceal smaller buildings behind them).
Skyscrapers Sudoku

Skyscrapers Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Consider each number to be the height of a building. The numbers outside the grid indicate how many buildings can be seen when looking in that direction (taller buildings conceal smaller buildings behind them).

 

Staircase Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Rows and columns span across the gaps in the diagram.
Staircase Sudoku

Staircase Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Rows and columns span across the gaps in the diagram.

 

Cupid Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • An arrow in a cell indicates that the number in this cell is repeated at least once in the direction the arrow points to.
Cupid Sudoku

Cupid Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • An arrow in a cell indicates that the number in this cell is repeated at least once in the direction the arrow points to.

 

Rossini Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • The arrows outside the grid indicate that the nearest three digits in the corresponding direction are in ascending or descending order (the highest number is always in the direction of the arrow). All possible arrows are given, so if there is no arrow, the first three digits do not form an increasing sequence in either direction.
Rossini Sudoku

Rossini Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • The arrows outside the grid indicate that the nearest three digits in the corresponding direction are in ascending or descending order (the highest number is always in the direction of the arrow). All possible arrows are given, so if there is no arrow, the first three digits do not form an increasing sequence in either direction.

 

Quotients Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • A number between two cells indicates the quotient of the numbers in these cells. A number between four cells indicates the quotient between two diagonally adjacent cells, either top left + right bottom (\) or top right + bottom left (/).
Quotients Sudoku

Quotients Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • A number between two cells indicates the quotient of the numbers in these cells. A number between four cells indicates the quotient between two diagonally adjacent cells, either top left + right bottom (\) or top right + bottom left (/).

 

Battenburg Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Everywhere 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given. A checkerboard pattern is a 2x2 area of cells where the top-left and bottom-right cells are of one type and the top-right and bottom-left cells are of another type. All possible dots are marked.
Battenburg Sudoku

Battenburg Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Everywhere 2 odd and 2 even digits form a 2x2 checkerboard pattern, a Battenburg marking is given. A checkerboard pattern is a 2x2 area of cells where the top-left and bottom-right cells are of one type and the top-right and bottom-left cells are of another type. All possible dots are marked.

 

Multi Diagonal Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Digits do not repeat along the marked diagonals.
Multi Diagonal Sudoku

Multi Diagonal Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Digits do not repeat along the marked diagonals.

 

Skyscrapers Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Consider each number to be the height of a building. The numbers outside the grid indicate how many buildings can be seen when looking in that direction (taller buildings conceal smaller buildings behind them).
Skyscrapers Sudoku

Skyscrapers Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Consider each number to be the height of a building. The numbers outside the grid indicate how many buildings can be seen when looking in that direction (taller buildings conceal smaller buildings behind them).

 

Mathrax Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Some intersections of the grid lines are marked by a number and an operator (+, -, x, /) in a circle. The number is the result of the operation, applied to both pairs of diagonally opposite cells. An E in the circle indicates that all four adjacent digits are even, while an O indicates that all four adjacent digits are odd.
Mathrax Sudoku

Mathrax Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Some intersections of the grid lines are marked by a number and an operator (+, -, x, /) in a circle. The number is the result of the operation, applied to both pairs of diagonally opposite cells. An E in the circle indicates that all four adjacent digits are even, while an O indicates that all four adjacent digits are odd.

 

Duodoku

  • Follow classic sudoku rules.This puzzle consists of tow overlapping grids of classic sudoku.
Duodoku

Duodoku

  • Follow classic sudoku rules.This puzzle consists of tow overlapping grids of classic sudoku.

 

Odd Even Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Cells with shaded squares contain even digits. Cells with shaded circles contain odd digits.
Odd Even Sudoku

Odd Even Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Cells with shaded squares contain even digits. Cells with shaded circles contain odd digits.

 

147 Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Cells with circles must contain digits 1-2-3, cells with squares must contain digits 4-5-6, blank cells must contains digits 7-8-9.
147 Sudoku

147 Sudoku

  • Place a digit from 1 to 9 into each of the empty squares so that each digit appears exactly once in each of the rows, columns and the nine outlined 3x3 regions.
  • Cells with circles must contain digits 1-2-3, cells with squares must contain digits 4-5-6, blank cells must contains digits 7-8-9.