Killer Sudoku is a combination of Sudoku and Kakuro. The goal of the game is to fill a 9x9 grid with numbers in such a way that each row, column, and 3x3 block contains all of the digits from 1 to 9, and the sum of the numbers in the cages (groups of cells surrounded by heavy lines) is equal to the target number in the corner of each cage.

Here's how to play Killer Sudoku Pro:

Familiarize yourself with the grid: The grid is a 9x9 square divided into smaller 3x3 squares called blocks. Each block, row, and column should contain all the digits from 1 to 9 without repetition.

Understand the cages: Cages are groups of cells surrounded by heavy lines, and each cage has a target number in the corner. The target number is the sum of all the digits in the cage.

Start filling in the numbers: Use logic and deduction to fill in the numbers starting with the cages that have only one cell. Then, fill in the remaining cages as you solve more of the puzzle.

Use the process of elimination: Keep track of which numbers have already been used in each row, column, and block. This will help you eliminate possibilities for the next number.

Check for errors: Regularly check your work to make sure you haven't made any mistakes.

Solve the puzzle: Keep filling in the numbers until the entire grid is complete.

Remember, in Killer Sudoku, each number can only be used once in each row, column, and block, and the sum of the numbers in each cage must equal the target number given in the cage.