Renban Sudoku (PuzzleMadness)

About Renban Sudoku (PuzzleMadness)

The usual sudoku rules apply: every row, column and 3x3 box holds 1 to 9 once each. Renban lines add a condition on the cells they pass through. A line covering four cells must hold four different consecutive digits, such as 3, 4, 5 and 6 or 6, 7, 8 and 9, but the order along the line does not matter: 5, 3, 6, 4 is just as valid. Lines can run straight, bend, or cut diagonally across boxes.

The rule is strongest on long lines, because a line of eight cells must contain either 1 to 8 or 2 to 9 and so is certain to include every digit from 2 to 8. A given digit on a line limits the run to digits close to it. Today's Medium grid, for example, has lines from two to five cells long.

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. Renban Sudoku comes in Easy, Medium, Hard and Tough versions plus a Mixed page, and the same day's Renban 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 Renban 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 Renban Sudoku (PuzzleMadness)

1. Open today's Renban 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. On each grey line, place a set of different, consecutive digits; their order along the line does not matter.
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

• A line of n cells can never contain digits that are n or more apart, so a 2 on a four-cell line rules out 6 and above.
• Long lines must include the middle digits: any run of five or more always contains 5.
• A line that stays inside one row, column or box cannot repeat a digit anyway, so focus on which run it can be.
• Missed a day? Earlier puzzles are in the archive, and finishing one still counts toward this month's leaderboard.

Questions