David Smith

Each puzzle consists of a 9x9 grid containing given clues in various places. The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each row, column and 3x3 box.

Each puzzle consists of a 9x9 grid containing given clues in various places. The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each row, column and 3x3 box.

Each puzzle consists of a 9x9 grid containing given clues in various places. The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each row, column and 3x3 box.

Each puzzle consists of a 9x9 grid containing given clues in various places. The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each row, column and 3x3 box.

Kropki Sudoku puzzles add black (o) and white (o) circles to a regular Sudoku puzzle. All pairs of touching squares which contain consecutive values (such as 2 & 3 or 6 & 7) are marked with a white circle: o. Also, all pairs of touching squares which contain values where one number is exactly twice the value of the other (such as 2 & 4, or 4 & 8) are marked with a black circle: o. This applies to left/right, up/down touching only - there are no diagonal markers. All possible o and o are given, so if there is no circle between two touching squares then they are not consecutive and one is not double the value of the other.

Kropki Sudoku puzzles add black (o) and white (o) circles to a regular Sudoku puzzle. All pairs of touching squares which contain consecutive values (such as 2 & 3 or 6 & 7) are marked with a white circle: o. Also, all pairs of touching squares which contain values where one number is exactly twice the value of the other (such as 2 & 4, or 4 & 8) are marked with a black circle: o. This applies to left/right, up/down touching only - there are no diagonal markers. All possible o and o are given, so if there is no circle between two touching squares then they are not consecutive and one is not double the value of the other.

Numbricks is a logic puzzle. It is played on a rectangular grid of squares. Some of the cells have numbers in them. The object is to fill in the missing numbers, in sequential order, going horizontally and vertically only. Diagonal paths are not allowed.

The rules of Jigsaw Sudoku are similar to standard Sudoku, since you must place each of the numbers 1 to 9 (or 1 to whatever the size of the puzzle is) into each of the rows and columns. However whereas standard Sudoku also has rectangular boxes that must each contain every number, in Jigsaw Sudoku these boxes are replaced by different bold-lined shapes that must each contain every number instead.

Grand Tour is a logic puzzle. It is a grid of points that all need to be connected by a single loop through all points of a rectangular or square grid. To begin the puzzle, a few of the points are already connected to insure a unique solution.

The rules of Jigsaw Sudoku are similar to standard Sudoku, since you must place each of the numbers 1 to 9 (or 1 to whatever the size of the puzzle is) into each of the rows and columns. However whereas standard Sudoku also has rectangular boxes that must each contain every number, in Jigsaw Sudoku these boxes are replaced by different bold-lined shapes that must each contain every number instead.

Outside Sudoku is a variation of the standard sudoku.Place numbers in the grid such that each row, column and 3x3 box contain the numbers 1 to 9. Outside cells must be inserted in one of the first three cells of the row or column.

Grand Tour is a logic puzzle. It is a grid of points that all need to be connected by a single loop through all points of a rectangular or square grid. To begin the puzzle, a few of the points are already connected to insure a unique solution.

Grand Tour is a logic puzzle. It is a grid of points that all need to be connected by a single loop through all points of a rectangular or square grid. To begin the puzzle, a few of the points are already connected to insure a unique solution.

Puzzle consists of a square grid. The goal is to fill in each cell with numbers from 1 to N, where N is the size of the puzzle's side. No number may appear twice in any row or column. The numbers along the edge of the puzzle indicate the number of buildings which you would see from that direction if there was a series of skyscrapers with heights equal the entries in that row or column.