CellBlocks (PuzzleMadness)

CellBlocks is PuzzleMadness's name for Shikaku, as the rules page says. The grid holds number clues, and you divide it into rectangles (squares count) so that each rectangle contains exactly one number and covers exactly that many cells. Every square of the grid belongs to one rectangle.

The daily page opens today's puzzle on its own, and its title carries the date (on 3 October 2026 it read "Daily Medium CellBlocks Puzzle for Saturday 3rd October 2026"). There is a separate dated puzzle for each size: Small, Medium, Large and Extra Large. The Mixed page is a fifth grid of its own, not a copy of one of the others, so a full day is five puzzles. 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 CellBlocks monthly and all-time leaderboards, where only your best score on any one puzzle counts.

Start with clues that can only grow one way, boxed in by the edge or other clues, and with prime numbers in tight spots, which can only be long thin strips. Large numbers in open areas come last, once their neighbours have taken their space.

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.