Sudoku Flow Unblocked

Classic 9x9 number logic with five levels, a custom clue slider, several modes, notes and hints that teach as they help.

Sudoku Flow is a tidy version of the familiar 9x9 number puzzle. Your job is to place the digits 1 through 9 so that each row, each column and each 3x3 box holds every digit exactly once. A handful of numbers are filled in at the start, and you reason out the rest.

Around that core it adds helpful extras: pencil notes, hints with three levels of detail, several play modes and a short set of lessons on solving methods.

Rules in brief

Pick an empty cell and choose a digit from the on-screen pad, or type it. The gray cells are the starting clues and cannot be changed. Put down a digit that conflicts with its row, column or box neighbors and the clashing cells flash, and the mistake counter goes up by one.

Every puzzle is generated so it has exactly one answer. That means you never need to guess, since pure logic always gets you to the end. When you want to track options, turn on Notes with the button or the N key and write small candidate digits in a cell.

Modes and difficulty

The New Game menu lets you set the level and the style of play.

• Five set levels run from Easy to Insane, and Custom lets you choose any clue count from 17 to 50.
• Classic is the standard game, and Zen is the relaxed one.
• Timed Rush gives you ten minutes, and Hardcore ends after three mistakes.
• Infinite deals a new puzzle as soon as you finish one.
• The Daily Challenge serves one medium puzzle for each calendar date.

Using hints wisely

Press H or the Hint button when you are stuck. In Settings you choose how much a hint gives away. Level 1 just points to a row, column or box worth checking. Level 2 names a cell and its digit. Level 3 fills in the cell and tells you the technique behind it. Unless you change the setting, a hint also puts a 30-second penalty on the clock and lowers your score.

Strategy notes

Start with lines and boxes that are missing only one or two numbers. Then take a single digit, such as 4, and look through each box for the one place it can still fit. Clicking any filled cell lights up every copy of that digit, which makes this scan much faster.

On Expert and Insane grids, notes become essential. Once candidates are written in, pairs and patterns are easier to see. The Learn section walks through methods ranging from simple singles up to advanced patterns such as X-Wing and Swordfish.

Your grid, notes and timer are saved in the browser as you go, along with best times, a daily streak and achievements. Six color themes, from Light to Midnight, let you set the look you like.

Controls