Penciller Number Logic

Penciller is a calm, handsome take on classic 9x9 Sudoku, drawn to feel like solving a puzzle in a well-worn letterpress notebook. Warm paper, graphite clues, and serif numerals keep your eyes comfortable while your mind does the heavy lifting. No accounts, no ads, no sound — just you and the grid.

Every puzzle is generated fresh. A backtracking engine builds a complete, valid solution and then carefully removes numbers while a uniqueness check guarantees exactly one answer — so every board is fair and solvable by logic alone, never by guessing.

FOUR DIFFICULTIES
• Easy — a gentle warm-up with plenty of clues.
• Medium — a balanced daily challenge.
• Hard — fewer clues, deeper deductions.
• Expert — sparse and demanding, for seasoned solvers.

BUILT FOR REAL SOLVING
• Pencil marks — jot small candidate notes into a cell's corners, just like on paper. Placing a final digit automatically tidies matching notes from its row, column, and box.
• Smart highlighting — the selected cell lights up along with its row, column, box, and every matching number, so patterns jump out.
• Conflict marking — duplicate digits are flagged instantly, and a wrong entry gives a quiet buzz.
• Hints — stuck on a cell? Reveal one correct digit and keep moving.
• Mistake counter — track your accuracy without ever being punished; experiment as much as you like.

TRACK YOUR PROGRESS
• Automatic save — close the app any time; your grid, timer, and notes are waiting when you return.
• Best times per difficulty, win percentage, and win streaks.
• Awards to unlock as you improve, from your First Solve to an Expert Draft.

LEARN THE GAME
New to Sudoku? The How to Play section explains the rules in plain language and includes a quick "valid placement?" practice mini-game to sharpen the one skill every solve depends on: knowing whether a digit can legally go in a cell.

DESIGNED TO RESPECT YOU
• 100% offline — no internet permission at all.
• No advertising, no trackers, no analytics, no third-party SDKs.
• No sound — feedback is purely visual plus gentle vibration.
• Portrait, one-handed friendly, and easy on the battery.

Whether you want a two-minute Easy break or a long Expert grind, Penciller keeps the focus where it belongs: on the numbers. Sharpen your pencil and start solving.