About playkillersudoku.app

Sudoku in its modern form traces to the late 1970s, when a puzzle called Number Place appeared in an American magazine; it was Japan’s Nikoli that named it and made it a worldwide craze in the 2000s. Killer Sudoku followed almost immediately. It grew out of the Japanese puzzle scene under the name samunanpure — “sum number place” — and spread to Western newspapers in the mid-2000s, where it picked up the name Killer Sudoku, and the alternatives sumdoku and sudoku killer.

The appeal is that it is a different kind of thinking to a clue-based sudoku. Instead of scanning for a lone missing digit, you reason about which digits can add up to a cage, then let the usual sudoku constraints trim the list. It borrows from kakuro, where sums are the clues, and combines that with the placement logic of sudoku.

Each puzzle starts as a complete, valid sudoku solution built from a random seed. The generator then carves the grid into connected cages whose sizes follow the chosen difficulty, keeping every digit in a cage distinct, and computes each cage total from the solution.

A solver then checks the result. It is cage-aware — it prunes candidates using the possible digit sets of every cage — and it stops as soon as it finds a second solution. If one exists, the generator splits the offending cage and tries again. Only when the solver confirms exactly one solution is the puzzle shown to you. The whole process runs in your browser in well under a second, which is why there is no puzzle database and no waiting on a server.