Sudoku & Logic Puzzles
A true logic puzzle has one correct answer and gives you every clue you need to reach it: no luck, no reflexes, just careful reasoning one step at a time. This page collects the pen-and-paper classics among the games on MathLogic: sudoku from gentle to fiendish, nonograms that turn number clues into pictures, minesweeper, detective deduction grids and spatial puzzles like tangrams and the Tower of Hanoi. All of them are free in the browser and most let you take as long as you like.
New to a puzzle type? Our guides cover four sudoku techniques, whether minesweeper is luck or skill and how to crack a cryptogram. For sorting, screw and block puzzles, see all logic games.
Sudoku
Fill the 9×9 grid so every row, column and 3×3 box holds the digits 1 to 9 once. Choose a level that matches your mood, or try killer and X-sudoku when the classic grid feels easy.
Nonograms and number grids
The numbers beside each row and column tell you how many cells to fill, and a picture appears as you work. Tiled Farm uses the same kind of counting logic with animals that stretch across the grid.
Minesweeper
Every number tells you how many mines touch that square. Read the patterns to clear the board safely, or take turns against a rival in the two-player version.
Deduction and code-breaking
Detective grids where you rule options out until one suspect is left, a safe to crack from written clues, letter-swap cryptograms and a higher-or-lower number hunt that rewards halving the range each time.
Shapes and paths
Spatial logic: rebuild outlines with tangram pieces, move a stack of disks in as few moves as possible, and connect or fill every cell of a grid with a single set of paths.
Sudoku and logic puzzles FAQ
What counts as a logic puzzle?
A puzzle you solve by reasoning from clues rather than by luck, speed or general knowledge. A well-made one has exactly one solution, and you can reach it without guessing. Sudoku, nonograms, deduction grids and most of minesweeper fit that description.
How many clues does a sudoku need?
At least 17. In 2012 mathematicians used a large computer search to show that no standard 9×9 sudoku with only 16 starting digits has a single unique solution. Fewer clues does not always mean a harder puzzle: difficulty depends on which solving techniques the grid forces you to use.
What is a nonogram?
A picture logic puzzle, also called hanjie or paint by numbers. Each row and column has a list of numbers giving the lengths of the filled blocks in that line, in order. Working out which cells must be filled, and which must stay empty, slowly reveals a hidden image.
How many moves does the Tower of Hanoi take?
With n disks the shortest solution takes 2ⁿ − 1 moves: 7 moves for 3 disks, 15 for 4 and 31 for 5. The trick is to think recursively: move the smaller stack out of the way, move the biggest disk, then put the smaller stack back on top.