Start with tight cages
Check two-cell cages with very small or large totals. In 4×4, a two-cell cage totaling 3 can only contain 1 and 2.
Killer Sudoku
A mobile-first Killer Sudoku game with 4×4, 6×6, and 9×9 sum-cage puzzles, 120 progressive levels, daily challenges, notes, sound, and account-free sharing.
Level 5 / 120
YouToStem · Logic
Σ Killer Sudoku · 4×4 Mini
Time0:00
Moves0
Cages solved2/9
Friend time—
No repeats in any row, column, or box. Digits in each dashed cage are unique and add up to its corner clue.
📘 Killer Sudoku Strategy Guide
Cross-check Sudoku rules
A cage gives combinations, while rows, columns, and boxes eliminate them. List the possible cage digits, then remove values already visible in each unit.
Digits cannot repeat in a cage
A repeated pair is illegal even when its arithmetic total works. This extra rule often removes an otherwise tempting combination.
Use unit totals
Every 4×4 unit totals 10, every 6×6 unit totals 21, and every 9×9 unit totals 45. Subtract completed cages to reveal a missing value.
❓ Killer Sudoku FAQ
How is Killer Sudoku different from regular Sudoku?
Rows, columns, and boxes still contain unique digits. In addition, digits cannot repeat inside a dashed cage and must add up to the small total in its corner.
Which board sizes and levels are included?
The campaign uses one continuous 1–120 progression: levels 1–40 are 4×4 Mini, 41–80 are 6×6 Junior, and 81–120 are 9×9 Killer. Next Level moves naturally into the following board stage.
Does every puzzle have one solution?
Yes. Each puzzle starts from a Sudoku grid already verified by the solver to have one solution. Cage totals add constraints and therefore cannot introduce another solution.
When is a cage considered correct?
After every cell is filled, its digits must total the corner clue and may not repeat. The game also marks a cage immediately when a partial total exceeds its target.
How does the Daily Puzzle work?
The date, selected size, and deterministic generator form the daily seed. Everyone playing the same stage on the same date receives the same puzzle without a stored backend puzzle list.
Can I challenge a friend without signing in?
Yes. Invite Challenge creates a URL containing the deterministic puzzle seed and your time, then opens the site-wide share dialog. The recipient gets the identical board.
Which solving aids are available?
Candidate notes, live conflict feedback, Undo, Erase, Hint, Restart, touch controls, and physical number keys are included. Browser level memory also returns players to their latest campaign level.
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