Fixing detection mistakes

After an import, the solver shows Check the dots and asks you to Compare with your game. Take that literally. Hold the game next to the board and check every dot before you tap Solve puzzle. A single wrong dot is the usual reason a board that has an answer comes back as No solution.

Check the grid size first

The label above the board gives its size as rows × columns, such as "7 × 7". If that doesn't match your game, every dot past the missing or extra line lands in the wrong cell, and editing dots one by one won't fix it.

For an imported image, tap Adjust outline, correct the count with the minus and plus buttons next to Rows and Columns, check that the faint yellow lines sit on the image's grid lines, and tap Find dots. Do this before you change any dots, because Find dots reads the image again and replaces your edits.

For a board you started with Blank board or opened from a file, Rows and Columns controls appear below the color list instead. They add or remove cells along the bottom and right edges and keep everything else in place.

Read the color list

Below the heading, every color on the board appears as a small swatch. A check mark means that color has exactly two dots. A warning sign with a count such as 1/2 or 3/2 means it doesn't. The board circles every dot of a flagged color, and a warning says One color doesn't have exactly two dots. Tap a circled cell to fix it. While any color is flagged, Solve puzzle stays disabled and the panel says Each color needs exactly two dots.

The list catches most mistakes. It can't see a dot sitting in the wrong cell, a pair missed completely, or an extra pair. If your game shows how many colors the level has, compare that number with the list.

Editing a cell

Tap or click any cell to select it. A panel titled Set this cell appears (on a phone, in place of the buttons at the bottom of the screen). It offers these choices.

• one swatch for each color already on the board, named by color and letter, such as "Red (A)",
• New color, which adds a color the board doesn't have yet,
• Empty cell, which removes a dot,
• Hole (not part of the board), which takes the cell out of the puzzle.

Tap the selected cell again, or the close button, to deselect it. When cells are too small to tap accurately, use the zoom button above the board (Zoom in to edit) and drag to move around.

On a computer, the keyboard is faster. Click the board once so it has focus, then use these keys.

Key	Effect
Arrow keys	Move the selection. The first press selects a cell.
A to Z	Put that letter's dot in the cell. The cell stays selected.
., Backspace or Delete	Empty the cell.
#	Make the cell a hole.
Escape	Deselect.
Enter	Select a cell, or move to the color swatches if one is selected.

The letters are labels. After an import they follow the order in which dots were found, row by row from the top, and each color is shown as it looked in your image. Typing a letter that isn't on the board yet starts a new color.

The usual mistakes

A missed dot

The color shows 1/2. Select the cell where the missing dot belongs and pick that color's swatch. The detector needs a bright, colored center to see a dot, so very dark dots, and dots under glare in a photo, are the ones it misses.

An extra dot

A dot appears where your game has none, usually from a drawn path segment or a reflection. If it formed a color of its own, that color shows 1/2. If it joined an existing color, that color shows 3/2. Select the cell and choose Empty cell.

Two colors merged into one

The detector groups dots by hue and ignores brightness. White and gray dots, or a red and a dark red, can come back as one color with 4/2. Select one dot of the second color and choose New color. Then select its partner and pick the new swatch.

One color split in two

Uneven light in a photo can make two dots of one color look different. You get two colors with 1/2 each and swatches of nearly the same shade. Select one of the two dots and pick the other color's swatch.

Holes

The detector never marks holes. If your game's board has missing cells, notches or gaps, they come in as empty cells, and the solver will try to fill them. That usually ends in No solution, or in an answer that runs through cells your game doesn't have. Select each missing cell and press #, or choose Hole (not part of the board).

A misread dot the list can't catch

Here every color shows two dots, so the list looks fine. The solver still reports No solution.

The cause is one Purple dot a single cell away from its place in the game. On a board where every cell must be filled, moving any one dot of a solvable board a single step up, down, left or right always makes it unsolvable. Color the cells like a checkerboard. The step moves the dot onto the other shade, which upsets a count that every filled board has to balance, and no arrangement of paths can repair it. Checkerboard parity explains the count.

When a board you trust comes back as No solution, look for this mistake first by comparing each dot's position with the game.

Editing as text

For bigger changes, open the menu (the three dots at the top right) and choose Edit as text. The board appears with One line per row. A–Z are dots (two per color), . is an empty cell and # is a hole. Fix it there and tap Apply. If the text can't be read as a board, the dialog explains why and Apply stays disabled. The full rules are in The .flow file format.

When the board matches your game, tap Solve puzzle. If the result still surprises you, Timeouts and “no solution” lists what else to check.