Sudoku: Classic Number Puzzle

Free classic sudoku, offline, with no account. 650 sudoku puzzles from easy to expert, plus a new daily sudoku challenge. A logic puzzle for brain training, with hints that explain the reasoning instead of just handing over a digit. Fill the grid so every row, column and box holds 1 to 9 once each. Tap a square, tap a number. That is the game. THE DIFFICULTY IS MEASURED, NOT GUESSED Most sudoku apps set difficulty by counting the clues they removed, a famously bad measure. Every puzzle here was solved the way a person solves one, technique by technique, and graded by the hardest it needed. Easy Scanning only, and plenty of clues to scan. Medium The same reasoning, with much less to go on. Hard Where a digit cannot go, not just where it can. Expert Pairs, triples and patterns across two units. NO GUESSING, EVER A sudoku with more than one answer is a trap: you fill a grid that breaks no rule and the game says you are wrong. Every board was checked twice: once for a single answer, once to confirm pure logic finishes it. HINTS THAT EXPLAIN, NOT HINTS THAT ANSWER "The answer is 7" teaches nothing and trains you to press it again. Every hint gives the reason first: "In box 2 every remaining 5 sits in the same column, so no other square in that column can be a 5." Read it and go back to the grid, or take the digit. The first hint on each puzzle is free. NEVER PLAYED BEFORE? START HERE A guided first puzzle names each rule at the moment you need it. It is on the home screen and in the settings menu. 650 PUZZLES, AND A NEW ONE EVERY DAY 200 easy, 200 medium, 150 hard and 100 expert, all offline. Plus a daily puzzle, the same board for everybody, with a visible streak and an advert to bring back a lapsed one. EVERYTHING THAT MAKES A SUDOKU PLEASANT Pencil marks, free and unlimited, with an optional one-tap fill. Placing a right digit clears it from the marks of every square that can see it. Unlimited undo, and erase any square at any time. Tap a number to light up every place it sits and every square you have pencilled it into, and the row, column and box you are working in. Duplicates show up as you type them. A timer you can ignore, your fastest time at each band, and quiet music with its own switch. EARN PENCILS, SPEND THEM ON LOOKS Every puzzle pays pencils, more for a harder board and more for a clean one, plus a daily handful that grows the longer your run lasts. Pencils buy your pencil colour, the paper the grid is printed on and the colour that lights up matching numbers. None makes a puzzle easier and none can be bought with money. BOOSTERS, AND FAIR ADS Nibs, from a daily gift and the solver ranks, buy three boosters: fill in one square, find every mistake including bad pencil marks, or take five moves back. Nibs can be bought too, but nothing is locked: all 650 puzzles are there from the first launch, undo and restarting are free, and every booster does what an AD button already does for free. A banner sits at the foot of the puzzle screen only, in a strip kept clear so the grid never moves. A short advert may play when you leave a solved puzzle, never mid-puzzle and never before your third. Every other advert is a button marked AD that names what it gives, beside a free choice. One purchase removes the banner and the between-puzzle advert. Three wrong digits stop a puzzle. Watch an advert to keep your grid, or start again: free, always. No energy. No lives to wait for. Works offline, with no account.