Pencilwork: Hard Logic Puzzles

Pencilwork brings Killer Sudoku, Kakuro, Loop, Bridges and big Nonograms together in one logic puzzle game for people who solve with pencil marks. Every puzzle is graded by the techniques it needs, hints name the technique, and there are no ads.

A new daily puzzle of each type every day, climbing from Easy on Monday to Expert on Saturday.

FIVE TYPES, FOUR LEVELS
- Killer Sudoku: 9x9 Sudoku with sums in dashed cages
- Kakuro: crossword-style sums with the digits 1 to 9 (also known as cross sums), 8x8 to 11x11
- Loop: draw one closed loop; each number counts the sides of its square the loop uses. 8x8 to 15x15
- Bridges: join every island into one group; each number says how many bridges meet it. 9x9 to 15x15
- Nonogram: big boards from 15x15 to 25x25, with hidden pictures and symmetric patterns
Every type comes in Easy, Medium, Hard and Expert.

GRADED BEFORE YOU START
Each puzzle is graded by the hardest technique its solution needs, plus a score. A start card shows the grade before the clock runs, for example "Hard · 4,382 · needs: Cage split, Innie/outie difference, Hidden pair". The grade is the one the solver found on that puzzle, not a label picked in advance.

HINTS THAT NAME THE TECHNIQUE
A hint starts with a nudge, then shows the reasoning on the board, and only then makes the move. It names the step: "45 rule: innie or outie", "Naked pair", "3 in a corner", "Closed group". In Killer Sudoku and Kakuro it checks your marks first and tells you if they removed the right digit. Hints are unlimited.

MARKS AND TOOLS
- Corner and centre marks, and 9 colours, up to 2 per cell, in Killer Sudoku and Kakuro
- Drag to select many cells and mark them at once
- A combination line for the selected cage or run, with the combinations your digits and centre marks rule out struck through
- Fill candidates once, or keep Auto-candidates on (both count as assists)
- Loop: lines, crosses, and inside or outside shading. Bridges: drag from island to island, and cross out ways that take no bridge
- Undo and redo, and a Restart you can undo
- Pinch to zoom big boards, with the clues pinned while you pan

FAIR PLAY
- The timer is on by default, and Pause covers the board so times stay honest. Hide it in Settings if you like
- Conflict checking shows only what the rules prove wrong. Turn it off, or check against the solution (counted as an assist)
- Every puzzle has one solution and can be solved by logic from a blank board. The hardest steps can need a short trial to a contradiction, and the hint says so
- A clean solve means no hints and no assists

STATS FOR SOLVERS
Best and median time for each level, a time chart, techniques seen, clean solves, and your daily and clean-solve streaks.

A LAB NOTEBOOK LOOK
- Designed dark first: graphite, one amber accent and tabular digits
- A light graph-paper theme too, or follow your phone
- Large text and High contrast settings
- Screen-reader actions on every board
- Every board plays from a hardware keyboard, with P to pause and H for a hint

WHAT'S FREE AND WHAT'S PREMIUM
Always free:
- Today's daily of every type, on a weekly ladder up to Expert.
- Unlimited Easy puzzles of every type.
- Every hint, pencil-mark mode, stat and theme, dark mode included.

Pencilwork Premium adds:
- Unlimited Medium, Hard and Expert in every type.
- The archive of past dailies.
- Every puzzle type added to Pencilwork later.

Premium is one Lifetime purchase: $14.99 (US price), paid once. There is no subscription and no trial: today's dailies and Easy puzzles are the way to try it. The app shows your local price before you buy.

PRIVATE AND OFFLINE
- No ads at any price
- No account or sign-in
- Plays offline
- Your puzzles, settings and stats stay on your device; we never receive them. Purchases are checked with our purchase service, RevenueCat, using an anonymous ID.

Questions or ideas? Our email address is on this page.