Paper Mode

Paper Mode lets you manage candidate notes entirely by hand, just like solving a Sudoku on paper. The grid starts empty — no auto-filled candidates — and you decide which candidates to write in, which to cross out, and when a cell is ready for a value.

Why Paper Mode?

In standard mode, the app automatically fills every empty cell with all valid candidates and keeps them in sync as you solve. This is convenient, but it skips a fundamental part of the solving process: working out which candidates belong where.

Paper Mode is for solvers who want the full experience:

• Build your own candidate grid — pencil in candidates cell by cell, just as you would on paper
• Train your eye — spot patterns by actively managing candidates rather than scanning a pre-filled grid
• Get help when you need it — the hint system adapts to what you've written, nudging you to fill in missing candidates before showing technique hints

Starting a Puzzle in Paper Mode

Paper Mode must be enabled before starting a new puzzle. You cannot switch a running game to Paper Mode.

There are two ways to enable it:

• New Game / Custom Game screen — a Paper Mode toggle appears directly on the screen before you start, available for Standard and Deep profiles
• Settings — enable Paper Mode in the settings; it will apply to the next game you start

When you begin a new puzzle with Paper Mode on, the grid shows only the given digits — no candidate notes at all.

Note: The Relaxed profile does not support Paper Mode. The toggle only appears for Standard and Deep profiles.

How It Works

Placing Values

You can place a value in any cell at any time — the smart keyboard shows all digits that are valid for the cell (not blocked by peers), even if you haven't noted them as candidates yet. You don't need to add a candidate before placing its value.

Filling in Candidates

Switch to note mode and tap digits to add or remove candidates in a cell. Build up your candidate grid at your own pace — there's no requirement to fill everything at once.

Housekeeping

The Housekeeping toggle controls what happens to peer candidates when you place a value:

• On (default): Placing a value automatically removes that digit from notes in the same row, column, and box — the same as standard mode
• Off: Notes are left untouched. You manage all eliminations yourself

Even with Housekeeping off, the hint system detects stale candidates (notes invalidated by placed values) and offers a Cleanup hint to remove them.

Auto-Complete

When a cell has only one candidate remaining and you've filled in enough surrounding candidates for the app to confirm it, the cell auto-completes — just like in standard mode. If you haven't noted enough candidates nearby, the cell waits until you do.

Auto-Highlights

When your notes are complete and correct — every valid candidate is noted and there are no stale entries — auto-highlights appear (hidden single indicators, bi-value cell markers), just as in standard mode. They disappear if your notes fall out of sync.

The Hint System

The hint system adapts to the state of your notes, guiding you through three stages:

1. Cleanup

If you have candidates that are no longer valid (a placed value eliminates them), the hint system offers a Cleanup hint first. It highlights the offending placed values, shows their influence across the grid, and marks the stale candidates for removal.

2. Coverage Nudge

If the next available technique requires candidates you haven't filled in yet, the hint system shows a coverage nudge — telling you which digits to add and where, so the technique becomes visible.

3. Technique Hint

Once your notes cover the requirements for a technique, the full technique hint appears — pattern cells, eliminations, and explanation — exactly as in standard mode.

Scanner

The technique scanner shows all available techniques in the puzzle. However, you can only select a technique when your notes fully cover all valid candidates. Until then, the list is visible (so you know what's available) but techniques cannot be activated. A message explains why.

Stylus Support

Paper Mode pairs naturally with a stylus. When a stylus is detected (Apple Pencil, S Pen, or similar), pressure sensitivity adds a physical dimension to solving:

• Light pressure — enters candidate notes, just like lightly pencilling in possibilities
• Firm pressure — places a value, like writing with conviction

This lets you switch between noting candidates and placing values without tapping mode buttons — press lightly to explore, press firmly to commit.

Adjust the pressure threshold in Stylus Settings to match your writing style.

Saving and Resuming

Paper Mode games save your notes alongside the puzzle state. When you resume, your notes are restored exactly as you left them.

If you resume a Paper Mode save with a profile that doesn't support Paper Mode, the app warns you that resuming will exit Paper Mode.

Tips

• Start with the easy digits — pick a digit that appears frequently in the givens and pencil in its remaining candidates across the grid
• Work row by row or box by box — systematic coverage helps you avoid gaps that block the hint system
• Use Housekeeping until you're comfortable — it handles the tedious part (removing placed digits from peers) while you focus on candidate discovery
• Watch for auto-highlights — when they appear, your notes are complete and correct. If they disappear after a move, something needs attention
• Use the Cleanup hint — it's the fastest way to tidy stale candidates after placing values with Housekeeping off