Killer Sudoku adds cage sums to classic Sudoku, delivering an advanced logic mode with deeper deduction. Play beginner to extreme difficulty, use pencil notes, and practice with error-free mode.
- Killer Sudoku with cages and sum constraints, no starting digits - Six difficulty tiers: Beginner, Easy, Medium, Hard, Expert, Extreme - Notes mode enabled by default, hints explain cage combinations - Practice mode removes mistake limits for learning - Daily Killer Sudoku available with UTC seed consistency