The History of Kakuro
Like Sudoku, Kakuro started life in an American puzzle magazine under a different name, and only became a household word decades later on the other side of the Pacific.
Cross Sums, Invented in America
The number-crossword puzzle now known as Kakuro first appeared in the United States under the name "Cross Sums" (also written "Cross Sum") in puzzle magazines from the publisher Dell; the earliest known example dates from 1950. Its invention is often credited to the Canadian Jacob E. Funk. It took some years to catch on, but by the mid-1960s it was a regular feature in Dell's puzzle magazines alongside Dell's other number and logic puzzles.
The idea combined the look of a crossword grid with arithmetic instead of vocabulary: black cells carrying clue numbers in place of crossword definitions, and white cells to fill in with digits whose sums had to match those clues.
A Japanese Name for a Second Life
Cross Sums crossed over to Japan, where the puzzle publisher Nikoli - the same company that would later popularize and name Sudoku - picked it up and gave it the name "Kakuro", a contraction of "kasan kurosu" (加算クロス), Japanese for "addition cross".
Through the 1980s, Kakuro grew into one of Nikoli's most popular puzzles in Japan, developing a following there well before the Sudoku boom that would later carry Nikoli's name to the rest of the world.
A Puzzle Rediscovered
Kakuro's international profile rose again in the mid-2000s in the wake of Sudoku's worldwide newspaper boom, as puzzle editors looking for a follow-up act turned to Nikoli's other number puzzles - introducing Kakuro to many Western solvers for the first time under its Japanese name, even though the puzzle itself had been invented decades earlier in North America.
That two-stage history is reflected in how the puzzle is still solved today: a Kakuro grid never needs guesswork, only the same run-by-run elimination Dell's original Cross Sums solvers used - simply expressed digit by digit, one clue at a time, the same principle this collection's generator uses in reverse to build a fresh puzzle out of a randomly filled grid.
A Note on the Names
The names 数独 (Sudoku), カックロ (Kakuro) and スリザーリンク (Slitherlink) are registered trademarks of the publisher Nikoli in Japan, and 橋をかけろ (Hashiwokakero) is the name under which Nikoli publishes that puzzle. PaperGames is not affiliated with Nikoli, is not endorsed or reviewed by Nikoli, and therefore uses other names in its Japanese version. The puzzle types themselves are free; every puzzle here is generated fresh on the device.