Killer Sudoku blog

Strategy guides, solving techniques, and tips for every level. Start with the complete strategy guide, then learn the 45 rule. Prefer to just play? Jump in below.

• Sumdoku, Sum Sudoku & Killer Sudoku: Why It Has So Many Names

  Sumdoku, sum sudoku, samunamupure, addition sudoku — they're all killer sudoku. Here's where each name comes from and why one puzzle ended up with so many.

• Killer Sudoku Strategy: The Complete Guide From Beginner to Expert

  A complete killer sudoku strategy guide, from your first cage to expert innies-and-outies. Learn the 45 rule, cage combinations, and the order to apply every technique.

• How to Solve Killer Sudoku: A Step-by-Step Guide for Beginners

  Learn how to solve killer sudoku step by step. A beginner's walkthrough of cages, your first moves, and a full worked example — no math degree required.

• 15 Killer Sudoku Tips and Tricks to Solve Puzzles Faster

  15 practical killer sudoku tips and tricks to solve faster — from locked cages and the 45 rule to combination shortcuts and the mistakes that slow you down.

• What Is the 45 Rule in Killer Sudoku? Innies and Outies Explained

  The 45 rule is the most powerful technique in killer sudoku. Learn what it is, how to use innies and outies, and how to crack hard grids with simple subtraction.

• Killer Sudoku vs Regular Sudoku: What's the Difference?

  Killer sudoku vs regular sudoku: the rules, the difficulty, and which to play. A clear comparison of cages, sums, and how the two puzzles really differ.

• Advanced Killer Sudoku Techniques: Cage Splitting, Chains & Forcing

  Advanced killer sudoku techniques for expert solvers: multi-region 45-rule splits, cage interaction chains, combination forcing, and adapted X-Wings.

• The History of Killer Sudoku: How 'Sum Number Place' Was Born

  The history of killer sudoku, from its Japanese 'samunamupure' roots and Latin-square ancestry to the UK newspaper boom that gave it the killer name.

• Does Killer Sudoku Require Math? What Beginners Get Wrong

  Does killer sudoku require math? Not really. Learn why killer sudoku is a logic puzzle with light arithmetic, and what beginners get wrong about the numbers.