SumSudoku, also known as Killer Sudoku, are addictive logic puzzles best described as a cross between Sudoku and Kakuro. Using pure logic and simple add/subtract calculations, these fascinating puzzles offer endless fun and intellectual entertainment to puzzle fans of all skills and ages. Each puzzle consists of a 9x9 Sudoku grid containing areas surrounded by dark borders. The object is to fill all empty squares so that the numbers 1 to 9 appear exactly once in each row, column and 3x3 box, and the sum of the numbers in each area is equal to the clue in the area's top-left corner. In addition, no number may be used in the same area more than once. The game includes helpful features such as showing possible sum number combinations in an area and pencilmarks to make temporary placement of numbers in the grid. For more fun, Conceptis SumSudoku includes a Weekly Bonus section providing an extra free puzzle each week. PUZZLE FEATURES • 90 free SumSudoku puzzle samples • Extra bonus puzzle published free each week • Multiple difficulty levels from easy to very hard • Puzzle library continuously updates with new content • Manually selected, top quality puzzles • Unique solution for each puzzle • Hours of intellectual challenge and fun • Sharpens logic and improves cognitive skills GAMING FEATURES • Concurrently playing and saving multiple puzzles • Puzzle library sorting and hiding options • Portrait and landscape screen support (tablet only) • Pencilmarks feature for solving hard puzzles • Show possible sum combinations option • Lock number on keypad option • Highlight Excluded Squares option • Unlimited Undo and Redo • Show conflicts during gameplay • Check puzzle • Track puzzle solving times ABOUT Conceptis SumSudoku have also become popular under other names such as Killer Sudoku, Sumdoku and Sumoku. All puzzles in this app are produced by Conceptis Ltd. - the leading supplier of logic puzzles to printed and electronic gaming media all over the world. On average, more than 20 million Conceptis puzzles are solved each day in newspapers, magazines, books and online as well as on artphones and tablets across the world.