Frame Sudoku (PuzzleMadness)

The usual sudoku rules apply: 1 to 9 once in every row, column and 3x3 box. Outside the grid, rows and columns carry a clue at each end, and each clue gives the total of the first three cells from that side. Not every grid prints all 36. On 28 October 2026 the Medium and Mixed grids had gaps in the frame, while the other levels showed the full set. In the site's example the first clue on the left is 14, and the first three cells of that row are 3, 7 and 4.

The site points out one trick that the harder grids need. Each row and column adds up to 45, so if the clues at the two ends of a row are 18 and 16, the three middle cells must total 45 minus 18 minus 16, which is 11. The frame clues also match the box structure, since each clue covers one box's slice of a line, so the three clues for a box's rows (or columns) together add up to 45.

The grid works like every sudoku on PuzzleMadness: number buttons above and below it, an eraser, and a pencil mode for candidate digits. On a keyboard, the number keys enter digits, the arrow keys move between cells, Ctrl, Shift or Alt with a number adds a pencil mark, and Delete or Backspace clears a cell.

PuzzleMadness is a free puzzle website run by Dewi, a software developer who started out making games for the PlayStation 2, Nintendo Wii and DS and now builds the site as a hobby. It carries dozens of puzzle types, from classic sudoku to newer logic grids, and each one gets its own dated puzzle every day at each difficulty. Frame Sudoku has four fixed levels from Easy to Tough. The Mixed page is a fifth grid of its own whose level changes from day to day, so everyone who visits shares the same five puzzles.

The site checks your grid as you go and tells you when it is finished; it does not publish solutions. Each completed puzzle earns a score, and scores feed a monthly and an all-time Frame Sudoku leaderboard, where only your best attempt at a puzzle counts. Older days stay in the archive, so a missed puzzle can still be played later and still counts toward the current month. Playing needs no account; a free registration gives you a username on the leaderboards and a cloud save. The pages carry adverts.