CrispSudoku

Classic, Killer, Thermo & more

Free · Designed for iPad. Not verified for macOS.

Five Sudoku variants, six grid sizes, a daily challenge, and a built-in tutor that explains every move. No ads, no tracking, fully offline. CrispSudoku is a polished, ad-free Sudoku game with real depth — five rule variants, six grid sizes, and a built-in tutor that explains how to solve every board. PLAY YOUR WAY • Five variants: Classic, Jigsaw (irregular regions), Sudoku-X (diagonals), Killer (summed cages) and Thermo (digits climb along each thermometer) • Six grid sizes: 4×4, 6×6, 8×8, 9×9, 10×10 and 12×12 • Four difficulties, from Easy to Expert • A new Daily Challenge every day — the same board for everyone LEARN AS YOU PLAY • "Explain the solve" walks through any board step by step, naming each technique (naked singles, hidden singles, locked candidates, X-wing and more) • "Next logical step" hints tell you what to play next, and why • Every puzzle gets an honest difficulty rating based on the hardest technique it actually requires THOUGHTFUL TOUCHES • Pencil-mark notes, unlimited undo, and live conflict highlighting • A mistake limit that scales with difficulty • Per-difficulty hint budgets, so hints stay meaningful • Beautiful themes you unlock as you play • Achievements, streaks and detailed statistics PRIVATE BY DESIGN • 100% offline — no account, no ads, no tracking, no data collection • Every puzzle is guaranteed to have exactly one solution CrispSudoku is free software, open source under the GNU AGPL-3.0.

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Thermo Sudoku — a new variant. Digits climb from each thermometer's bulb to its tip. Every size up to 9×9, and most boards need no starting digits at all: the thermometers alone are enough to pin the grid down. Also in this update: • A much bigger board on small and folding phones. On a compact screen the grid had been taking about half the width — it now fills it. • Landscape is a real layout instead of a squeeze: the controls sit beside the board rather than above and below it. • Everything holds together at large accessibility text sizes, in English and German. • Explain the solve fits the screen it is on, so the whole board and the explanation are visible at once. • Pencil marks are readable again on 10×10 and 12×12 boards. • Killer puzzles now draw their cages correctly in every build. • Fixed a startup problem that could leave the game showing a blank screen.

The developer, Christian Strobele, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .

  • Data Not Collected

    The developer does not collect any data from this app.

    Privacy practices may vary, for example, based on the features you use or your age. Learn More

    The developer has not yet indicated which accessibility features this app supports. Learn More

    Seller
    Christian Strobele
    Size
    20.6 MB
    Category
    Puzzle
    Compatibility
    Requires iOS 15.0 or later.
    • iPhone
      Requires iOS 15.0 or later.
    • iPad
      Requires iPadOS 15.0 or later.
    • iPod touch
      Requires iOS 15.0 or later.
    • Mac
      Requires macOS 12.0 or later and a Mac with Apple M1 chip or later.
    • Apple Vision
      Requires visionOS 1.0 or later.
    Languages
    English
    Age Rating
    4+
    Copyright
    © 2026 Christian Ströbele