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Fillomino is a grid-based logic puzzle published by the Japanese company Nikoli. The objective is to divide the grid into regions known as polyominoes. Each cell within a given region must contain a number equal to the total number of cells in that region. While some numbers are provided as starting...

Thermo-Sudoku is a variant of the traditional Sudoku puzzle that incorporates a constraint based on thermometer-shaped lines drawn on the grid. Along each thermometer line, digits must strictly increase in value starting from the unnumbered bulb end and moving toward the tip. Standard Sudoku rules s...

KenKen is an arithmetic logic puzzle invented in 2004 by Japanese educator Tetsuya Miyamoto, who developed it as a teaching tool for his classroom. The puzzle is played on a square grid in which each row and column must contain the digits 1 through N without repetition, forming a Latin square. The g...

German Whispers Sudoku is a variant of Sudoku in which a supplementary constraint applies to marked lines within the grid: adjacent digits along each marked line must differ by at least 5. The constraint is named after the party game 'telephone' ('Chinese whispers' or 'German whispers'), reflecting...

Arrow Sudoku is a logic puzzle variant that overlays standard Sudoku rules with arithmetic constraints. The grid features arrows originating from empty circles. The digit placed in a circled cell must equal the sum of the digits placed along the corresponding arrow's path. While standard Sudoku rule...

Renban Sudoku is a variation of the standard Sudoku puzzle that introduces "Renban lines," which are often highlighted in a distinct color. The digits placed along each of these lines must form a set of consecutive, non-repeating integers, though they can be arranged in any order. For example, a lin...

Skyscrapers is a logic-based combinatorial puzzle originating in Japan that is built on the Latin square mathematical model. The puzzle is played on an N×N grid where the objective is to fill each cell with a height from 1 to N without repeating numbers in any row or column. Numbers placed around th...

Skyscraper Sudoku is a logic puzzle variant that combines standard Sudoku rules with a spatial visibility constraint. Solvers place digits from 1 to 9 into a grid, treating each number as a building of that specific height. Numeric clues provided outside the grid's perimeter indicate how many buildi...

Calcudoku is a grid-based arithmetic puzzle that follows a format similar to KenKen. Solvers fill a square grid with digits, ensuring that no number repeats within any row or column. The grid is divided into outlined blocks called cages, each containing a target number and an arithmetic operation. T...

Irregular Sudoku, frequently called Jigsaw Sudoku, is a logic puzzle variant that modifies the structural regions of standard Sudoku. Instead of the traditional nine 3x3 boxes, the grid is partitioned into irregularly shaped regions of nine cells each. The solving objective remains to fill the grid...

Ripple Effect, also known as Hakyuu, is a number-placement logic puzzle published by Nikoli. The grid is divided into irregularly shaped rooms, and each room of size N must contain the integers 1 through N. Identical numbers placed in the same row or column must be separated by at least that number...

Suguru, also called Tectonics, is a Japanese number puzzle published by Nikoli in which each polyomino region of n cells is filled with the integers 1 through n, and no two equal numbers may touch, even diagonally.

Little Killer Sudoku is a Sudoku variant in which clues placed outside the grid indicate the sum of digits along specified diagonals. Unlike standard Killer Sudoku, where cage sums constrain grouped cells, Little Killer Sudoku allows digit repetition along diagonals because diagonal cells are not bo...

Sandwich Sudoku is a Sudoku variant in which additional clues placed outside the grid indicate the sum of the digits positioned between the 1 and the 9 in each row and column. The name derives from the concept that the intervening digits are sandwiched between those two values. Standard Sudoku rules...

A magic square is an arrangement of distinct integers in a square grid where every row, column, and main diagonal sum to the same constant, with the earliest known example appearing in Chinese literature as the Lo Shu around 650 BCE.

Sudoku is a classic logic puzzle involving a nine-square grid. Players strategically place numbers one through nine to complete each row, column, and three-box section. It’s notable for its ability to sharpen logical thinking skills and remains popular with individuals seeking a challenging mental e...

Bulls and Cows is a classic code-breaking logic game in which one player thinks of a secret, usually four-digit, number and the other tries to guess it. After each guess, the first player provides feedback: a "bull" indicates a correct digit in the correct position, while a "cow" indicates a correct...

Between Lines Sudoku is a logic puzzle variant designed for enthusiasts of constraint-based grid deduction. In this format, digits are placed along line segments that connect two circled endpoint cells. The numerical value of every digit along the line segment must fall strictly between the values o...

Binairo, also known as Takuzu or Binary Puzzle, is a logic puzzle played on a rectangular or square grid where cells must be filled with zeros and ones. The objective is to ensure that each row and column contains an equal number of both digits and that no more than two identical numbers appear cons...

A Latin square puzzle is a mathematical logic challenge played on a square grid, directly derived from concepts explored by mathematician Leonhard Euler in the 18th century. The fundamental rule requires filling an n-by-n grid with n distinct symbols so that each symbol appears exactly once in every...

XV Sudoku is a logic puzzle variant that applies mathematical constraints to a standard Sudoku grid. Orthogonally adjacent cells may be marked with an X to indicate their values sum to 10, or a V to indicate their values sum to 5. In many variations, the absence of a mark between adjacent cells indi...

Palindrome Sudoku is a variant of Sudoku that adds one or more designated lines to the standard 9×9 grid. Along each marked line, the sequence of digits must read identically in both directions, meaning the digit at one end must match the digit at the opposite end, the second digit must match the pe...

Samurai Sudoku is a Sudoku variant consisting of five overlapping 9×9 Sudoku grids arranged in a quincunx pattern, with the central grid sharing one 3×3 box with each of the four surrounding grids. The combined puzzle spans a 21×21 cell area, though overlapping regions are counted only once. Each of...

Anti-King Sudoku is a Sudoku variant that adds a spatial constraint inspired by chess to the standard 9×9 grid. In addition to normal Sudoku requirements that each row, column, and 3×3 box contain digits 1 through 9 exactly once, the anti-king rule prohibits identical digits from appearing in any tw...

Str8ts is a logic-based number puzzle invented by Jeff Widderich and popularized by fellow puzzle designer Andrew Stuart. Solvers are presented with a grid containing both white and black cells, where the black cells act as blockers similar to those in a crossword puzzle. The objective is to fill th...

Nonconsecutive Sudoku is a mathematical logic puzzle that applies an additional global constraint to the standard Sudoku grid. While solvers must still ensure that each row, column, and 3x3 box contains the digits one through nine without repetition, a specific spatial restriction is enforced. No tw...

Consecutive Sudoku is a logic puzzle variant that adds specific spatial constraints to the traditional 9x9 Sudoku grid. In this puzzle, a thick line or bar is used to mark the border between any two orthogonally adjacent cells that contain consecutive numbers. The defining mechanic is that the absen...

2048 is a mobile puzzle game centered around combining numbered tiles to achieve a final tile of 2048. Its notable simplicity and challenging gameplay create an addictive experience for players who enjoy strategic thinking and quick reflexes. The game is suitable for anyone seeking a casual, single-...

Kurotto is a grid-based logic puzzle published by the Japanese company Nikoli. The puzzle is played on a rectangular grid where certain cells contain numbers enclosed in circles. The objective is to shade specific cells black so that the number in each circled cell accurately represents the total si...