Killer Sudoku is a fun and challenging variant of Sudoku that is now available on iPhone. If you are a fan of Sudoku, why not give Killer Sudoku a try?

Similar to Sudoku, the objective of Killer Sudoku is to fill the grid with the numbers 1 to 9, ensuring that each row, column, and nonet (3x3 group of cells) contains each number only once. However, Killer Sudoku adds an extra twist by dividing the grid into cages, which are shown with dashed lines. Each cage has a sum displayed in the top-left corner, and the numbers within the cage must add up to that sum. Additionally, no number can appear more than once in a cage.

The app comes with ten puzzles for free, and there are thousands more available for download. The puzzles are graded into different difficulty levels, ensuring that there is a challenge for everyone. The quality of the puzzles is excellent, and each puzzle has a unique solution.