Sudoku

Sudoku at The New York Times is the classic nine-by-nine number grid, published by New York Times Games and dated to the day, with three grids to choose from under Choose Your Puzzle: Easy, Medium and Hard. The rules are the ones the help panel states in three lines: fill each 3 x 3 set with the numbers 1 to 9, tap a cell and select a number, and keep going until the board is complete, since numbers in sets, rows or columns cannot repeat. What sets this version apart from a printed grid is the toolkit around it. A Normal mode places one number per cell, a Candidate mode pencils several options into a cell, and an Auto Candidate Mode fills those pencil marks for you. A timer runs and can be paused, an undo goes back several moves, and an error counter, conflict highlighting and row-and-column highlighting can each be switched on in the settings. New grids are released in the evening, Eastern time, on a fixed weekly schedule.

1. Open the Sudoku page and pick a level under Choose Your Puzzle: Easy, Medium or Hard. To switch levels later, tap Back in the toolbar.
2. Tap a cell in any 3 x 3 set, then select a number from the keypad; in Normal mode one number fills the cell.
3. Switch to Candidate mode to pencil several possible numbers into a cell, or turn on Auto Candidate Mode to have the options filled in for you.
4. Use the menu when stuck: Hint shows the next logical cell to solve, Check Cell or Check Puzzle verifies your entries, and Reveal Cell or Reveal Puzzle gives the answer away.
5. Fill every cell so that no number repeats in a set, row or column; each digit appears on the finished board exactly nine times.
6. Pause the timer from the toolbar if you step away, and resume it when you are back.

This is the Sudoku for people who want one dated set of grids rather than an endless generator: three levels a day, the same three for everyone, released on a newspaper schedule. It suits solvers who like pencil marks done properly, because Candidate mode and Auto Candidate Mode make the notation the game's own job. Skip it if you want unlimited grids of one difficulty on demand, or a past-puzzle archive without paying, since that archive sits behind the Games subscription. Expect a few minutes on Easy and a proper sit-down on Hard.

There is no guess limit and no penalty built into the grid: a wrong number sits there until you find it. How much the game tells you is up to the settings. With Check guesses when entered switched on, an incorrect entry is flagged the moment you place it; with Highlight conflicts on, a digit already present in the same row, column or box gets a conflict warning; with Show error counter on, every mistake adds to a running tally. On demand, Check Cell and Check Puzzle verify your entries, Reveal Cell and Reveal Puzzle hand over answers, and the timer records the solve, stopping whenever you pause it.

Easy

The first of the three grids for the day's date, chosen under Choose Your Puzzle. Same rules and same toolbar as the other two.

Medium

The middle grid of the day. The site tracks each difficulty separately, so finishing Easy does not put a check mark on Medium in the selector.

Hard

The most demanding grid of the trio. This is where Candidate mode and Auto Candidate Mode earn their place, and where Hint points to the next logical cell when the board stalls.

• Turn on Check guesses when entered in the settings if you want wrong numbers flagged immediately; leave it off for a purer solve where only Check Puzzle tells you.
• Start in auto candidate mode is a setting worth switching on for Hard grids: every cell shows its remaining options, and your attention goes to logic instead of bookkeeping.
• Highlight conflicts and Highlight row and column make a repeated digit visible at a glance, which is the most common slip in a fast Easy grid.
• Ask for a Hint before a Reveal: a hint only points to the next logical cell, so the solve stays yours.
• Show error counter turns mistakes into a score to beat; the site introduced it as an extra challenge alongside undo and highlights.
• The help panel gives the release times: Tuesday to Saturday puzzles at 10 p.m. Eastern, Sunday and Monday puzzles at 6 p.m. Eastern.