How to Play Little Killer Sudoku

Little Killer Sudoku is a variant where numbers appear outside the grid next to diagonal arrows. Each clue gives the sum of all cells along the diagonal that arrow points into. Unlike Killer Sudoku cages, digits may repeat along a Little Killer diagonal — the only uniqueness constraints are the standard row, column, and box rules.

In Killer Sudoku, cage digits cannot repeat. In Little Killer Sudoku, diagonal digits can repeat freely — only standard Sudoku uniqueness rules apply. This changes the solving logic significantly: you cannot directly eliminate combinations based on uniqueness within a diagonal.

Yes. Digits may repeat along a Little Killer diagonal as long as they are in different rows, columns, and boxes — which standard Sudoku rules enforce. For example, a 3-cell diagonal summing to 6 could be {1,1,4}, {1,2,3}, {2,2,2}, {3,2,1}, etc.

Start with the shortest diagonals. A 1-cell diagonal tells you the digit directly. A 2-cell diagonal with a very small or very large sum severely limits possible combinations. Then look for diagonals that intersect — where the same cell must satisfy two diagonal sum constraints simultaneously.

The core rule is straightforward. The challenge comes from the arithmetic of diagonal enumeration combined with the fact that digits can repeat. Beginners benefit from writing out all possible combinations for each diagonal before starting to eliminate. This habit makes the variant much more approachable.

Easy puzzles take 10–20 minutes. Medium puzzles run 20–40 minutes. Hard puzzles average 40–75 minutes and expert puzzles often exceed 90 minutes. Cross-diagonal intersection analysis is the key skill that distinguishes fast solvers from slower ones.