Hard Sudoku (Metro)

About Hard Sudoku (Metro)

Metro, the UK newspaper, runs a puzzles section on metro.co.uk with crosswords, Word Wheel, Hangman and sudoku in three levels. Hard Sudoku is the top level: Metro describes it as its hardest sudoku and as a daily, difficult puzzle for experts, to be played on a phone, tablet or computer.

The grid is a classic 9 by 9 sudoku. Some digits are given, and you fill the rest so that each row, column and 3 by 3 box holds 1 to 9 exactly once. On the hard level the givens are sparse, so the obvious placements run out early and you need pairs, pointing digits and other longer deductions to move on.

The puzzle plays right on the page with no account. Above the grid are Rules, Hint and Check buttons, and a number pad sits beside it. When you finish, the page tells you how long you took and offers a link to share the puzzle with friends. The hard grid comes Monday to Friday; at the weekend the page shows no grid, and Metro points paying readers to its Puzzles+ bundle instead.

It suits a solver who wants one demanding sudoku with the morning commute, with the easy and medium grids on the same menu for a warm-up. The page is free and carries ads.

How to play Hard Sudoku (Metro)

1. Open Hard Sudoku on metro.co.uk on a weekday; no sign-up is needed.
2. Select an empty cell in the 9 by 9 grid.
3. Enter a digit from 1 to 9 with the number pad or your keyboard.
4. Make sure each row, column and 3 by 3 box holds every digit once.
5. Press Hint for help when stuck, or Check to see whether your entries are right.
6. Fill every cell to finish, then share the puzzle with friends if you like.

Screenshots

Tips

• Scan each 3 by 3 box for digits that can only go in one cell before trying harder techniques.
• Look for pairs: two cells in a unit that can only hold the same two digits rule those digits out everywhere else in that unit.
• Use Check sparingly; one wrong digit early on a hard grid spreads, so it is worth checking before a long chain of placements.
• If the hard grid feels out of reach, try Metro's Medium Sudoku on the same menu first.

Questions