Killer Sudoku
(aka sumdoku, addoku, or samunamupure)
Killer sudoku has the same basic sudoku rules, but also adds an element that the sum of the cells in a cage must equal the total given for the cage. Below, the killer sudoku "cages" are marked as different colors. Inside of the cages will be a number. The sum of all the numbers in the cage will equal the number found inside the cage.
Example of killer sudoku puzzle grid