Between Line Sudoku (PuzzleMadness)

The normal rules of sudoku apply, with 1 to 9 once in every row, column and 3x3 box. Each Between line has a circle at both ends. The digits in the cells along the middle of the line must all lie strictly between the two circled digits, so a line from a 2 to a 7 can only hold 3, 4, 5 and 6 in its middle, and never 2 or 7 themselves. Either end can be the larger one.

The ends of a line are usually far apart in value, since a long line needs room for its middle digits: a line with three middle cells needs ends at least four apart. Circles cannot hold a digit equal to any middle cell, which also rules out 1 and 9 in the middle of any line. The Medium grid for 28 October 2026 had 13 lines, some only three cells long and others bending across two or three boxes.

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. Between Line Sudoku comes in Easy, Medium, Hard and Tough versions. The Mixed page is a fifth grid of its own, not a copy of one of the four, and its level changes from day to day. Each of the five is shared by everyone who opens it that day.

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 Between Line 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.