Daily Killer Jigsaw (SudokuWiki)

SudokuWiki.org is Andrew Stuart's sudoku strategy site, and among its numbered daily puzzles the Killer Jigsaw is one of the most demanding. It combines the rules of a jigsaw sudoku, where every row, every column and each of nine irregular regions must hold the digits 1 to 9, with those of a killer sudoku, where coloured cages carry a sum and their digits must add up to it without repeating.

Each puzzle has a number, a date and a difficulty level, #796 and Diabolical on 21 October 2026. The free page gives one grade a day; All-Access Supporters can play all four. The on-page player has a level picker, a number pad, notes that can be prefilled or cleared automatically, undo, redo, a check button, a timer with pause, print versions, and a link to the site's solver if you want to see the logic of a step.

Because the regions are irregular, the familiar 45-per-box sums of a killer sudoku apply to oddly shaped areas, which makes for some unusual deductions.

It suits experienced sudoku players who already enjoy killers and want a harder daily twist.