Consecutive Line Sudoku (PuzzleMadness)

About Consecutive Line Sudoku (PuzzleMadness)

Every row, column and 3x3 box still holds 1 to 9 once each. The lines add a chain condition: neighbouring cells along a line hold consecutive digits, so the line can step up, step down or zig-zag, as in 2, 3, 4, 5 or 6, 5, 4, 3, 2, 3, 4. Unlike Renban lines, the digits on a Consecutive line need not all be different; a repeat is fine when the two cells are in different rows, columns and boxes.

The lines also give a parity pattern for free: digits along a line alternate between odd and even, so one known digit tells you whether every other cell on the line is odd or even. Today's Medium grid, for example, has a few short lines and a longer one that climbs from the middle-left box into the centre box.

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. Consecutive Line Sudoku comes in Easy, Medium, Hard and Tough versions plus a Mixed page, and the same day's Consecutive Line Sudoku puzzle is shared by everyone who opens it.

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 Consecutive 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.

How to play Consecutive Line Sudoku (PuzzleMadness)

1. Open today's Consecutive Line Sudoku page on PuzzleMadness and choose a difficulty from the menu above the grid.
2. Click a cell and enter a digit with the number buttons above and below the grid or with the keyboard; the eraser button clears a cell.
3. Fill every row, column and 3x3 box with the digits 1 to 9, each once.
4. Along each grey line, make each digit exactly one more or one less than the digit next to it on the line.
5. Turn on pencil mode (the pencil button, or Ctrl, Shift or Alt with a number key) to jot candidate digits in a cell.
6. The site tells you when the grid is complete and adds your score; registered players appear on the leaderboards.

Screenshots

Tips

• Digits along a line alternate odd and even, so one given digit fixes the parity of the whole line.
• A 1 or a 9 on a line can only have a 2 or an 8 beside it.
• Cells two steps apart on a line differ by 0 or 2, which narrows candidates quickly in a box.
• Missed a day? Earlier puzzles are in the archive, and finishing one still counts toward this month's leaderboard.

Questions