Killer Sudoku follows the same rules as regular Sudoku in that each row, column and block must contain one of the numbers from "1" to "9". No number may appear more than once in any row, column, or block.
It differs in that it introduces "cages" - groups of adjacent 2, 3, 4, or 5 cells demarcated by dotted lines. Each cage indicates the total that it's cell values sum to.
For example, in the puzzle to the right, the cage shaded green has cells totalling 19. Also, the cells in each cage must be unique. Note that no cell values (fixed cells) are supplied in any puzzle.

All puzzles are solvable by pure logic alone - no guessing required. There are three new puzzles a day - one at each difficulty level. Be sure to read the walkthrough first.
You may find these puzzles more challenging than regular Sudoku - remember you can use the "Solve a Cell" feature to help you along.

How to play   Walkthrough   Video walkthrough