Grid Puzzles
Constraint-based logic puzzles played on grids. Every puzzle here gives you a set of rules and an empty (or partially filled) grid, and asks you to find the unique arrangement that satisfies all constraints. No math knowledge required, no vocabulary — just careful reasoning and elimination. Each puzzle type has five difficulty levels from beginner to Einstein.
Killer Sudoku
Sudoku with cage sums. Digits in each cage add up to a target — no repeats allowed.
Kakuro
Fill white cells with 1-9 so each entry adds up to its clue. No repeats within an entry. Also called cross sums.
Futoshiki
Fill the grid with 1–N, satisfying inequality symbols between cells. Also known as greater-than sudoku.
Skyscrapers
Place buildings by height so each row and column is a Latin square. Border clues tell you how many buildings are visible.
Binairo
Fill the grid with 0s and 1s. No three in a row, equal counts, unique rows and columns. Also known as takuzu.
Star Battle
Place stars so every row, column, and region has the right count. No two stars can touch, not even diagonally.
Light Up (Akari)
Place light bulbs to illuminate every cell. Bulbs shine along rows and columns until blocked by a wall.
Suguru
Fill each cage of N cells with 1 to N. No two identical digits may touch — not even diagonally.
Slitherlink
Draw a single closed loop along grid edges. Number clues tell you how many edges of each cell belong to the loop.
Hashi
Connect islands with bridges. Each island shows its bridge count. All islands must form one connected network.
What makes grid puzzles different
Killer Sudoku and Kakuro combine number placement with arithmetic — you need digits that satisfy both position rules and sum constraints. Futoshiki adds inequality operators between cells, creating chains of greater-than and less-than relationships you have to untangle.
Star Battle and Light Up are about placement under visibility constraints. In Star Battle no two stars can touch. In Light Up, bulbs illuminate entire rows and columns, and two bulbs must never see each other.
Hashi is the odd one out visually — instead of filling cells, you draw bridges between islands. But the underlying logic is the same: count constraints, connectivity rules, and a unique solution you reach through elimination.