Center-Dot Sudoku (PuzzleMadness)

Center-Dot Sudoku is a 9x9 sudoku with one extra region: the middle square of each 3x3 box is shaded grey, and those nine grey squares must hold 1 to 9 once between them. It is the same idea as the diagonals in X-Sudoku or the shaded boxes in Hyper Sudoku, applied to the box centres.

The daily page opens today's puzzle on its own, and its title carries the date (on 3 October 2026 it read "Daily Medium Center-Dot Sudoku Puzzle for Saturday 3rd October 2026 (Medium)"). There is a separate dated puzzle for each of Easy, Medium, Hard and Tough. The Mixed page is a fifth grid of its own. On 28 October 2026 it was labelled Medium yet held different givens from the Medium page. Past days stay in the archive, so a missed puzzle can be played later, and there is a print version and an image download of the grid. PuzzleMadness does not publish solutions: the site tells you when you have finished a grid correctly or made a mistake. Each completed puzzle adds to your total on the Center-Dot Sudoku monthly and all-time leaderboards, where only your best score on any one puzzle counts.

Treat the nine grey squares as a tenth box scattered around the grid. A digit already in one grey square cannot appear in any other, which often cuts a centre square down to one candidate. The rest is classic sudoku.

PuzzleMadness is a British puzzle site with dozens of daily puzzle types in the browser, from many sudoku variants to logic grids such as Nurikabe, Hashi and Slitherlink. It is free to play and carries ads. A free account keeps track of the puzzles you have finished and puts your name on the leaderboards, and the badges next to usernames mark how many puzzles a player has completed.