Suduro

Suduro is a new puzzle that blends the rules and challenges of Kakuro and Sudoku. As far as I know, I (Dan Tow) am the inventor of this game. In Suduro, you solve a Kakuro-like puzzle in the first stage, in order to create a Sudoku puzzle, which you then solve in the second stage using the usual strategies for solving Sudoku puzzles. However, there is no rule against beginning to solve the Sudoku puzzle when you have just a partial solution to the Kakuro-like puzzle, and this can be a good or even necessary strategy for completing stage

1. The rules are best illustrated by example, so here is the first Suduro puzzle I built, as an illustration:

The gray and white squares must be filled in with the numbers 1-9, just as for Sudoku. Just as Sudoku requires, each row, column, and 3-by-3 sub-grid (as outlined by the thicker black lines) uses each of the numbers 1-9 exactly once. However, unlike Sudoku, Suduro does not provide starting numbers for the problem solution by filling in roughly one-third of the grid squares in advance. Instead, Suduro shows some of the grid squares colored gray, and provides clues to the sums of groups of the gray squares, just as Kakuro provides sums of rows and columns of squares. In Suduro, the numbers in the black squares along the left edge of the puzzle are the sums of the gray squares in each row. The numbers in the black squares along the top edge of the puzzle are the sums of each column of gray squares. Finally, the numbers in the small 3-by-3 grid to the upper left of the main grid are the sums of the gray squares within each 3-by-3 sub-grid inside the main grid.

Examples will make this clearer, so I’ll illustrate the beginnings of the solution of this Suduro, with row and column labels added so I can refer to the rows and columns clearly.