Ninefold - Sudoku Logic Puzzle

About

Ninefold Sudoku is a brain-training sudoku built around one idea: every puzzle should teach you something. Instead of throwing random boards at you, it grades each level by the actual logic technique needed to solve it — so difficulty climbs smoothly and you genuinely get sharper. Whether you are a complete beginner learning the rules or a seasoned solver hunting X-Wings and chains, Ninefold meets you where you are and takes you further. DAILY CHALLENGE — ONE SHARED PUZZLE EVERY DAY Open the challenge calendar for a new puzzle shared by players around the world. Complete each date, build your daily streak and fill the month to earn its badge. Missed dates remain available in the archive, so you can revisit the board without rewriting your streak. THE CAMPAIGN — FIVE TRACKS, 5,000 LEVELS EACH Pick a difficulty track — Easy, Medium, Hard, Expert or Master — and work down it twenty levels at a time. Start with "only one number fits" and climb all the way to naked pairs, hidden triples, X-Wings, Swordfish, coloring and XY-chains. A technique lesson auto-appears only at its first formal introduction; later matching boards keep the Tips button without interrupting play. Every layer ends with a boss board. No sudden walls, no impossible jumps — a clean climb from rookie to master. THE TECHNIQUE LIBRARY — 14 ILLUSTRATED LESSONS Every core technique comes with a step-by-step illustrated card that shows you exactly why the deduction works. It appears the first time you meet the technique, and lives in Settings whenever you want another look. HELL MODE — FREE, AND THERE IS NO BOTTOM One run, five lives for the whole descent (seven with Premium), and a score. A correct digit pays, a combo multiplies what it pays, and a floor cleared without a slip doubles the bonus. A wrong digit costs a life and the combo — never points. No hints, no auto notes, and the same board for everyone. The floors keep coming; your deepest run earns a rank you keep and a poster you can share. BUILT TO SHARPEN YOUR MIND - Your Brain Profile tracks Focus, Logic and Memory and updates with every solve - Smart notes (pencil marks), gentle highlights and guided rows keep you thinking, not guessing - Best times, solve counts and 30-day trends show progress you can actually see FEELS GOOD TO PLAY Every move has a satisfying candy-brick response — tuned animation, sound and haptics that make solving feel great. Play in warm light, calm dark, or high-contrast paper themes. WHY YOU WILL LOVE IT - A true number logic puzzle, not luck — every board is solvable by pure reasoning - No account required and fully playable offline - No ads interrupting your solve - Free to start, with an optional Premium upgrade NINEFOLD PREMIUM (OPTIONAL) Ninefold is free to play. Ninefold Premium unlocks the full experience — every difficulty pack, unlimited mistakes throughout the Campaign, advanced statistics and extra board themes. Premium is available as a monthly or yearly auto-renewable subscription, or as a one-time Lifetime purchase. Prices are shown in the app and vary by region. Monthly and yearly subscriptions renew automatically unless auto-renew is turned off at least 24 hours before the end of the current period, and your Apple Account is charged for renewal within 24 hours before the period ends. You can manage or cancel those subscriptions anytime in your device Settings. Privacy Policy: https://gentleflow.github.io/legal/ninefold/privacy/ Terms of Use (EULA): https://gentleflow.github.io/legal/ninefold/terms/ Train your brain, one cell at a time. Download Ninefold Sudoku today.