Killer sudoku online
This board is killer mode: keep 1–9 once per row, column, and box, then use the cage sums in the corners. Digits cannot repeat inside a cage — that is the whole twist.
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Killer sudoku online
Killer sudoku keeps the usual rule — 1–9 once per row, column, and 3×3 box — and adds cages: outlined groups that must add to a printed sum. Digits inside a cage cannot repeat. That combination is the whole game: you still place numbers, but the sums cut the search space (and create new traps).
The board on this page is a killer puzzle, not a relabeled classic grid. If you only wanted plain sudoku, use the home board.
When
When to use
You searched killer sudoku; you like sum logic with normal digit rules; you want a harder variant without jumping to 16×16.
When not
When not to
You still need classic rules only → how to play sudoku. You want brutal classic difficulty without cages → evil sudoku or hard sudoku. You want strategy habits for plain grids → sudoku strategy.
Defaults
Assumptions
Standard killer: cages show a sum; no repeated digit inside a cage; classic row/column/box still apply. Cage shapes vary per puzzle. Unique solution. Browser play; no print pack.
Steps
How
- Read each cage sum; list digit combos that fit the cage size (e.g. 3 cells summing to 6 → 1+2+3).
- Cross-check with row/column/box — a combo that breaks a box is dead.
- Use Pencil for candidates; Hint when you want a named next step.
- New puzzle loads another killer; Check flags conflicts without dumping the full answer key.
Worked notes
Examples
- A 2-cell cage summing to 3 → must be {1,2} in some order — place them only where both row and box allow
- A cage sum of 45 in nine cells → the whole box (1–9 once); use it as a checksum, not a mystery
Watch-outs
Gotchas
- Killer is not “classic plus random circles.” If cages do nothing, you are on the wrong site.
- Digits cannot repeat inside a cage even if they would be fine across boxes otherwise.
- Solver-style pages that paste a finished grid teach little; use Hint for one step, not a full dump.
Nearby pages
Compare
Classic play: homeRules without cages: how to playHard classic: hard sudokuTechnique habits: sudoku strategy
Controls
Quick controls
- Hint — a cell/digit, technique name, and short reason.
- Check — flags conflicts without revealing the full grid.
- Pencil — candidate notes for empty cells.
- New puzzle — same difficulty band, fresh seed.
- Daily — fixed local seed for the calendar day.
- Erase — clear the selected cell (not givens).
FAQ
Common questions
What makes killer different?
Cage sums and no repeat inside a cage, on top of normal sudoku rules.
Do I need to know combo lists?
Helps a lot for small cages; Hint can nudge when you stall.
Is this the same as “sudoku killer” search?
Same puzzle family; this URL loads killer mode.
Daily killer?
Use Daily when shown; otherwise New puzzle for a fresh cage layout.