Sudoku Puzzles
Classic Sudoku and the variants that grew out of it. Every puzzle here is built on the same core idea: fill a grid with numbers so that no row or column repeats. What changes between variants is the extra constraint ā cage sums, overlapping grids, irregular shapes, or arithmetic operations. Five difficulty levels each, from easy grids that take a few minutes to Einstein puzzles that can eat an afternoon.
Sudoku
Fill the 9Ć9 grid so every row, column, and 3Ć3 box contains 1 through 9. The original number placement puzzle.
Killer Sudoku
Sudoku with cage sums. Digits in each cage add up to a target ā no repeats allowed. Combines placement logic with arithmetic.
Samurai Sudoku
Five overlapping 9Ć9 grids with shared boxes. Solving one grid gives you clues for the next. Cross-grid logic required.
Jigsaw Sudoku
Sudoku with irregular jigsaw-shaped regions instead of 3Ć3 boxes. Same row and column rules, different spatial reasoning. Also called squiggly sudoku.
KenKen
Fill the grid with 1āN so no number repeats in any row or column. Cages have a target number and arithmetic operation ā add, subtract, multiply, or divide.
Futoshiki
Fill the grid with 1āN so no number repeats in any row or column. Inequality signs between cells tell you which is larger. Also known as greater-than sudoku.
How the variants differ
Standard Sudoku is pure elimination. You look at what numbers are already placed in a row, column, or box and work out what's missing. At higher difficulties you need techniques like X-wing, swordfish, or chain analysis ā spots where you hold multiple possibilities in your head and see which leads to a contradiction.
Killer Sudoku adds cage arithmetic on top of the standard rules. Each dotted cage has a sum, and the digits inside can't repeat. You end up reasoning about both what fits the sum and what fits the row or column, and the intersection of those two constraints is where the puzzle cracks open.
Samurai Sudoku is five 9Ć9 grids arranged in an X pattern, sharing corner boxes. You can't solve any single grid in isolation ā progress in one spills clues into the overlapping regions of another. The puzzles are physically larger and take longer, but the logic stays familiar if you already know Sudoku.
Jigsaw Sudoku replaces the 3Ć3 boxes with irregular shapes. The row and column rules are identical, but the uneven regions change which cells interact. If you rely on box-based shortcuts in regular Sudoku, jigsaw forces you to read the grid differently.
KenKen is the furthest from standard Sudoku. The grid can be any size from 3Ć3 to 9Ć9, and each cage specifies an arithmetic operation ā add, subtract, multiply, or divide ā plus a target result. Smaller grids are approachable for kids. The larger ones get genuinely hard, because the number of possible cage combinations explodes.
Futoshiki strips things back. Same Latin square rule ā fill with 1āN, no repeats ā but instead of cages or sums, you get inequality signs between adjacent cells. A ā>ā between two cells means the left must be larger. The puzzles look sparse, but the chains of inequalities constrain more than you'd expect.
Tips that apply to all Sudoku variants
Start with the most constrained cells. In standard Sudoku that means rows, columns, or boxes with the most given digits. In Killer Sudoku it's small cages with few possible combinations. In KenKen it's single-cell cages (they just tell you the answer outright).
Use pencil marks. Writing candidate numbers into empty cells is annoying but pays off on harder puzzles. Every variant here has a Notes mode ā use it once you get past medium difficulty.
When you're stuck, look for pairs. Two cells in a row that can only hold the same two numbers? Those two numbers are locked out of every other cell in that row. This works in every Sudoku variant, and it's the single most useful technique after basic elimination.