About Killer Sudoku on Suvi
A hard killer sudoku on Suvi has bigger cages, up to five squares, and needs at least one step beyond the basics: the rule of 45 across two or three rows or columns at once, trying a cage's combinations square by square, or a hidden pair. Our solver checks that before you see it, and checks that the grid has one solution you can reach without guessing. Pencil marks, undo and the Combos list are there so you can work it through on your phone without paper. Take your time: a clean solve is worth sharing.
How to play
- Fill the 9×9 grid so every row, every column and every 3×3 box holds the numbers 1 to 9 once.
- The dashed outlines are cages. The numbers in a cage must add up to the small total in its corner, and can't repeat inside it.
- Tap a square, then a number. Tap Pencil to jot down candidates instead; Undo takes back your last move.
- Tap Combos to see every set of numbers that fits the cage you're in: three squares adding up to 7 can only be 1, 2 and 4.
- Stuck? A hint fills one square and says why.
Controls
On a phone or tablet: Tap a square, then a number on the pad. Tap Pencil for candidate notes and Combos for the sets of numbers that fit the cage. The grid fits your screen without zooming.
On a desktop: Click a square or use the arrow keys. Type 1–9 to fill, Backspace to clear, P for pencil marks, C for combos, U to undo.
Tips
- Start with the cages that have only one combination: two squares adding up to 3 must be 1 and 2, and three squares adding up to 24 must be 7, 8 and 9.
- Every row, column and box adds up to 45. If the cages wholly inside a box total 38, the one square poking in from outside must be 7.
- A one-square cage is a free number: its total is its digit.
- If a cage sits wholly inside one row or box and all its combinations share a number, that number can't be anywhere else in that row or box.
- Pencil marks pay off on Hard: note the few numbers a square can take, then look for the one that's left.
Questions
- Is Killer Sudoku free?
- Yes. Today's puzzles at all three levels are free every day, plus a few extra practice puzzles. While Suvi is new, every past puzzle is free to everyone too.
- How is killer sudoku different from sudoku?
- No numbers are given at the start. The cages and their totals are the clues: work out which numbers can make each total, then use the usual sudoku rules for rows, columns and boxes.
- Does every puzzle have one solution?
- Always. Each grid is checked by our solver before you see it, and it can finish every one with logic alone, so you never have to guess.
- What is the rule of 45?
- The numbers 1 to 9 add up to 45, so every row, column and box does too. Add up the cages wholly inside one, and the squares left over must make up the difference, which often gives you a number outright.
- Is it the same puzzle for everyone?
- Yes. Each day's puzzle at each level is the same for every player and changes at midnight in your own time zone, so you can race a friend on it.
- Can I play on my phone?
- Suvi is built for phones first: the grid fits a portrait screen with big tap targets, and the cage totals stay readable. It works just as well on a tablet or a computer.
More Killer Sudoku
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- Mines — The classic minefield, with a daily board everyone shares and a marked safe start.
Who made it
Killer Sudoku is a Suvi Original, written and tested by Brasslight Games. Every puzzle is generated and checked by our own tools; nothing is copied from another site.