Addoku (also known as Killer Sudoku) is a variation on the well-known Sudoku puzzle that tests your capabilities in both logic and arithmetic. It's a regular Sudoku grid, but to fill it in you need to use your knowledge of addition.

Addoku Plus takes the arithmetic a step further, introducing subtraction, multiplication, and division.

For a change of pace, there are also regular Sudokus to be solved.

Features:
- Create and solve Sudoku, Addoku and Addoku Plus puzzles
- Millions of puzzles available
- Ten levels of difficulty
- Checkpoint and restore the puzzle state
- Undo/redo
- Progress information
- Save your unfinished puzzle and return to it later
- Online tutorial, including solving a puzzle step by step