Kakuro: Global Reach & Resource Directory
History & Origins
Kakuro began life in 1966 as Cross Sums, created by Jacob E. Funk (Canadian) while working for Dell Magazines in the United States. Some sources trace an earlier appearance to the April/May 1950 issue of Official Crossword Puzzles, also through Dell.
In 1980, Japanese publisher Nikoli introduced the puzzle to Japan under the name Kasan Kurosu ("addition cross"). Players soon shortened it to Kakuro, and Nikoli formalized that name in 1986. By the early 1990s Kakuro was the most popular logic puzzle in Japanese print media — a position it held until Sudoku displaced it in 1992. It remains Japan's second most popular logic puzzle today.
The UK wave arrived in September 2005, when The Guardian and The Daily Mail both launched daily Kakuro columns. International syndication followed quickly, and the puzzle now appears in 35+ countries.
Notable Authors & Constructors
| Name | Country | Notable for |
|---|---|---|
| Jacob E. Funk (ref) | Canada | Created the original Cross Sums puzzle for Dell Magazines (1966) |
| Maki Kaji (1947–2021) | Japan | Founder of Nikoli; introduced Kakuro to Japan; known as "the Godfather of Sudoku" |
| Timothy E. Parker | USA | Guinness World Records Puzzle Master; "the world's most syndicated puzzle compiler"; founded Master Puzzles, Inc. (1999); syndicated in 120+ countries |
| Frank Longo | USA | Accomplished constructor; created a 50×50 Kakuro for the New York Times Puzzle Mania section |
| Thomas Snyder ("Dr. Sudoku") | USA | Kakuro author, multi-category puzzle champion, co-founder of GMPuzzles |
| Serkan Yürekli | Turkey | Constructor of Kakuro and original variations; prolific GMPuzzles contributor |
| Grant Fikes | USA | Contributing puzzlemaster, cross-genre constructor |
| Prasanna Seshadri | India | Contributing puzzlemaster; competitive solver |
Publishers
Japan
| Publisher | Notes |
|---|---|
| Nikoli | Japan's foremost logic puzzle publisher; originated the Kakuro craze; quarterly magazine Puzzle Communication Nikoli |
| Gakken | Major Japanese educational/puzzle publisher; carries Kakuro titles |
| Sekai Bunkasha | Japanese publisher with regular Kakuro output |
United States
| Publisher | Notes |
|---|---|
| Dell Magazines | Original publisher; home of Cross Sums since 1966; now operating as Penny Dell Puzzles |
| Master Puzzles, Inc. | Founded by Timothy Parker (1999); aggregates 60+ top puzzle masters |
| Sterling Publishing | Publishes Will Shortz puzzle collections including Kakuro volumes |
International Syndication
| Publisher | Notes |
|---|---|
| Conceptis Ltd. (Israel) | World's leading number-logic puzzle supplier; produces 25,000+ new puzzles per year; distributes Kakuro to 100+ countries through newspaper syndication |
| King Features Syndicate (USA) | Exclusive worldwide newspaper syndication partner for Conceptis Kakuro since January 30, 2006; delivers one Classic Kakuro per day (Very Easy Monday → Hard Sunday) |
| Creators Syndicate (USA) | Additional syndication channel for Conceptis content |
| Torstar Syndication Services (Canada) | Canadian syndication of Conceptis Kakuro |
United Kingdom
| Publisher | Notes |
|---|---|
| Puzzler® | Dedicated Kakuro magazine (subscription); regular puzzle features across its range of logic titles |
Newspapers & Magazines
Newspapers with Regular Kakuro
| Publication | Country | Notes |
|---|---|---|
| The Guardian | UK | Daily Kakuro since September 2005 |
| The Daily Mail | UK | Daily Kakuro since September 2005 |
| The Daily Telegraph | UK | Regular Kakuro features |
| King Features client papers | Worldwide (100+) | Daily syndicated Kakuro |
| Creators Syndicate client papers | Worldwide | Daily syndicated Kakuro |
Dedicated & Logic Puzzle Magazines
| Magazine | Country | Notes |
|---|---|---|
| Puzzle Communication Nikoli | Japan | Quarterly; flagship Nikoli publication; multiple Kakuro per issue |
| Kakuro (Puzzler®) | UK | Subscription; dedicated to Kakuro |
| Various Japanese logic magazines | Japan | 100+ Japanese publications carry Kakuro regularly |
Notable Book Collections
| Title | Author/Publisher |
|---|---|
| The Official Book of Kakuro: Book 1 | Timothy E. Parker (150 puzzles) |
| Mastering Kakuro | Timothy E. Parker (150 puzzles) |
| The Way of Kakuro: The King of Japanese Number Puzzles | Nikoli |
| Will Shortz Presents Easy Kakuro | Sterling Publishing (100 puzzles) |
| Mensa® Kakuro | Conceptis Puzzles |
| Little Book of Bathroom Kakuro | 200+ puzzles |
Online Puzzle Sites
| Site | URL | Notes |
|---|---|---|
| Kakuro.com | kakuro.com | Free; multiple difficulty levels (beginner to master) |
| Kakuro Conquest | kakuroconquest.com | Free; interactive; multiple difficulty levels |
| Free Kakuro | freekakuro.com | Free; candidate notes, hints, step-by-step guides; instant board generation |
| Kakuro-Online | kakuro-online.com | Free; timed daily challenges; puzzle generator |
| Kakuro Online | kakuros.com | Free online Kakuro |
| Krazydad | krazydad.com/kakuro | Thousands of free puzzles; printable and browser/iPad playable |
| ATK Solutions | atksolutions.com | Free; browser-based Cross Sums |
| Nikoli (Japan) | nikoli.co.jp | The original source; subscription access to official Nikoli puzzles |
Mobile & Platform Apps
iOS (iPhone/iPad)
| App | Developer | Notes |
|---|---|---|
| Kakuro | Mastersoft | Combo calculator; bookmarking; described as "most feature-rich mobile Kakuro" |
| Real Kakuro | Rottz Games | 3000+ unique puzzles; 10×10 board without zoom |
| Art of Kakuro | — | Unlimited puzzle generation (4×4 to 14×14); three difficulty levels |
| Kakuro: Number Crossword | — | iOS App Store |
| Kakuro Puzzle | — | iOS App Store |
Android
| App | Developer | Notes |
|---|---|---|
| Real Kakuro – Cross Sums | Rottz Games | "#1 Free Kakuro on mobile"; multiple difficulty levels; combination hints |
Consoles & PC
| Platform | Title | Notes |
|---|---|---|
| Nintendo Switch | Puzzle by Nikoli S: Kakuro | Official Nikoli title |
| Xbox | Puzzle by Nikoli W: Kakuro | Official Nikoli title |
| Steam (PC/Linux) | Kakuro | Steam App ID 1038690 |
Competitive & Organized Play
World Puzzle Championship (WPC)
- Annual international competition run by the World Puzzle Federation
- Kakuro is a recurring event alongside other pure-logic puzzles
- All puzzles are language-neutral, making international competition straightforward
- Scoring emphasizes solving speed
Kakuro's status as Japan's second most popular puzzle suggests regional club-level and magazine-sponsored competitions exist, though these are not widely documented outside Japan.
Related Puzzle Types
| Puzzle | Link | Relationship |
|---|---|---|
| Cross Sums | Wikipedia | Original English name for Kakuro; still used by Dell Magazines |
| Kasan Kurosu | Wikipedia | Original Japanese name ("addition cross"); used 1980–1986 |
| Killer Sudoku | Wikipedia | Arithmetic variant of Sudoku; cage sums, no repeated digits — shares DNA with Kakuro |
| KenKen / MathDoku | kenken.com · Wikipedia | Cage arithmetic puzzle using all four operations; similar skill set |
| Hitori | Wikipedia | Nikoli shading puzzle; shares the no-repeats-in-line constraint logic |
| Futoshiki | Wikipedia | Latin-square puzzle with inequality clues; related logical reasoning |
| Sumplete | sumplete.com | Modern sum-elimination grid puzzle; emerging genre |
Academic & Research
Computational Complexity
Kakuro is proven NP-complete, meaning no known polynomial-time algorithm can solve all instances. Key papers:
| Paper | Authors/Venue | Link |
|---|---|---|
| "The Computational Complexity of the Kakuro Puzzle, Revisited" | Fun with Algorithms (5th International Conference); Springer | Springer |
| "Solving Kakuro Puzzle using Self Adapting Harmony Search Metaheuristic Algorithm" | Academia.edu | Academia.edu |
| "KAKURO SOLVER APPLICATION" | NDSU Library | NDSU |
| ASP-Completeness framework (covers Kakuro) | arXiv | arXiv |
Solving Approaches
- Backtracking search — systematic trial-and-error with pruning; most common in software solvers
- Constraint propagation — eliminate candidates through run intersections before backtracking
- Self Adapting Harmony Search (SAHS) — metaheuristic; pre-filters valid sum combinations
- SAT solvers — encode puzzle constraints as Boolean satisfiability; general-purpose approach
- Smith Normal Form / lattice reduction — mathematical approach for combinatorial analysis
Global Reach at a Glance
| Metric | Figure |
|---|---|
| Countries publishing Kakuro | 35+ |
| Japanese magazines carrying Kakuro | 100+ |
| Conceptis annual puzzle output | 25,000+ new puzzles |
| Conceptis distribution countries | 100+ |
| Timothy Parker syndication reach | 120+ countries |
| King Features newspaper clients | Worldwide daily distribution since 2006 |
| Japan ranking | #2 logic puzzle (after Sudoku) |
| Japan historical peak | #1 logic puzzle (until 1992) |
| Major free online sites | 8+ |
| iOS apps | 5+ |
| Console/PC platforms | Nintendo Switch, Xbox, Steam |
Key Sources & Further Reading
- Kakuro — Wikipedia
- Nikoli (publisher) — Wikipedia
- Maki Kaji — Wikipedia
- History of Kakuro Puzzles — WMC Publishing
- Conceptis Kakuro product page
- King Features / Conceptis syndication announcement
- Remembering Maki Kaji — Nippon.com
- Kakuro rules & info — GMPuzzles
- Computational Complexity paper — Springer
- World Puzzle Championship — Wikipedia
- Puzzler® — puzzler.com
- Timothy E. Parker — official site