Suko (PuzzleMadness)

Suko is a small number puzzle on a 3x3 grid. Each of the digits 1 to 9 goes in once. Four circles sit where four squares meet, and each circle's number is the sum of those four squares. The squares are also split into three colours, and the totals above the grid say what each colour group adds up to. The site notes that Suko is a trademark of Kobayaashi Studios.

The daily page opens today's puzzle on its own, and its title carries the date (on 28 October 2026 it read "Daily Medium Suko Puzzle for Wednesday 28th October 2026 (Medium)"). There are four grids a day. Easy, Medium and Hard each have their own, and the Mixed page serves a fourth grid whose level changes from day to day. On 28 October it was marked Hard but held a different layout from the Hard page. Past days stay in the archive, so a missed puzzle can be played later, and there is a print version of the grid. PuzzleMadness does not publish solutions. The grid tells you when it is complete and correct, and shows a score (45 for that day's Medium). Each completed puzzle adds to your total on the Suko monthly and all-time leaderboards once you have a free account, and only your best score on any one puzzle counts.

With only nine squares, Suko is quick, but it is pure arithmetic logic. The centre square is in all four quadrants, and the edge squares in two each, so comparing quadrant sums tells you differences between squares. Colour groups of two squares often have only a few possible pairs.

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.