Sly Arcade
Classic Sudoku
Fill the grid so every row, column and box contains 1–9.
PlaySudoku Variants
One grid. New ways to think.
Play six Sudoku variants in your browser: Classic, Diagonal, Jigsaw, Killer, Thermo and Arrow. Each variant has 200 original puzzles, each verified to have exactly one solution, with notes, undo and step-by-step hints: first where to look, then why, then the answer only when you ask. All puzzles are open.
Diagonal Sudoku
Solve a Sudoku grid with two extra no-repeat diagonals.
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Jigsaw Sudoku
Fit 1–9 into rows, columns and irregular regions.
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Killer Sudoku
Use cage totals and no-repeat rules to find the missing digits.
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Thermo Sudoku
Follow increasing thermometer paths to complete the grid.
Play
Arrow Sudoku
Make the digits along each arrow add up to its circle.
PlayStart with a familiar grid
Classic uses rows, columns and boxes. Diagonal adds two complete diagonals; Jigsaw replaces boxes with irregular nine-cell regions.
Try sums and paths
Killer combines no-repeat cages with totals. Thermo uses increasing paths. Arrow lets a circle set the total of its shaft, with repeats allowed across ordinary units.
Learn the next step
Hints begin with a region to inspect. Ask again for the proof and once more for the conclusion. They use candidate logic from your current board. Daily selections replay verified puzzles, rather than promising a new puzzle every day.
Explore the original guides