What Killer Sudoku Is
Killer Sudoku combines classic Sudoku logic with arithmetic cages. Every move must satisfy both the standard grid rules and the target sums shown inside dashed cages.
How It Is Different From Classic Sudoku
In classic Sudoku, you only care about rows, columns, and 3x3 boxes. In Killer Sudoku, you also use cage totals to narrow down the possible numbers much earlier.
How to Use Cage Sums
Start by checking the number of cells in a cage and its target sum. Smaller cages often have only a few possible number combinations, which makes them perfect entry points.
How to Use Notes
Turn on note mode to mark candidates before committing. Notes help you compare cage combinations, row pressure, and box restrictions without guessing.
How the Daily Challenge Works
There is one public puzzle each day. Your timer starts when you begin the challenge or make your first meaningful move, and your final board is verified on the server before submission.
How the Top 10 Leaderboard Works
The Top 10 is sorted by accuracy first, then speed. Fewer mistakes rank higher. If two runs have the same mistake count, the faster solve time wins.