KillSud - Killer Sudoku is a puzzle game that offers a challenging variation of the classic Sudoku game. Developed by BotenSoft, this app is available for Android devices and is free to download.

The game follows the rules of regular Sudoku, but with two additional rules that make it even more challenging. First, the sum of all numbers in a cage must match the small number printed in its corner. Second, no number can appear more than once in a cage. With over 4,000 puzzles ranging from easy to complicated, KillSud is sure to keep you entertained for hours.

The app also includes a special sum calculator to help you choose the right numbers, as well as detailed help available under the "menu" option. Additionally, the game features an auto-save and auto-restore function for ongoing puzzles, and the ability to undo moves (no redo). If you encounter any bugs while playing, you can email the developer directly with details. It's important to note that bugs should not be reported in reviews.

Overall, KillSud - Killer Sudoku is a fun and challenging puzzle game that is perfect for Sudoku enthusiasts who are looking for a new twist on the classic game.