Killer Sudoku
Use ordinary Sudoku rules plus cage sums. Every source in this release is checked for exactly one solution under its starter and cage constraints. V0.183 includes 50 verified sources across five Practice tiers and eight symmetry transforms per source. Expert removes one additional starter from each Hard base; Pure starts with zero given digits and is independently re-proved unique from cages alone.
Daily archive, local snapshots & display
Display choices stay only in this browser.
Save a second line of attack without replacing the normal autosave.
How to play & strategy
A two-cell cage totaling 3 can only use 1 and 2; a two-cell 17 can only use 8 and 9. The combination panel shows all unordered sets still possible for the selected cage.
Because every row, column and 3×3 box contains 1–9 once, each totals 45. Near-complete cage groups can reveal the leftover sum without guessing.
Progress stays in this browser. Daily Killer is separate from Today’s 6, and clean bests require no Hint and no checked mistake.
Advanced coach, calculator & local evidence
See why a move works — without reading the stored solution
The coach recomputes candidates from the current grid, row/column/box rules and cage sums. It can prove cage remainders, Rule-of-45 singles, naked singles, hidden singles and cage-locked digits; when that proof set cannot place a digit, it says so instead of inventing certainty.
Current-board logic
Analyzing the current board…
Independent cage calculator
Check any distinct-digit cage, including one that is not on this board. Optional include/exclude digits let you model eliminations explicitly.
No calculation yet.
Move review & turning point
No entered moves yet.
Same-setup evidence
Finish the same puzzle cleanly more than once to compare your local coach score.
Daily evidence
Recent 7 days by default; expand to 30. Local browser history only. No fabricated global percentile, rating, or population benchmark.