Killer Sudoku (aka Sumdoku / Mathdoku) is a Sudoku variant where cells are grouped into cages and the sums of the values in each cage are given. It's much more fun than normal Sudoku!

The app includes plenty of 4x4 and 6x6 puzzles for beginners and hundreds of 8x8 and 9x9 puzzles with varying degrees of difficulty for advanced users and expert solvers. Plus a sum calculator and cage summer to help you figure out possible matches and ability to validate progress.