Tips and common mistakes

Technique gets you through a puzzle. Habits get you through it quickly, and keep you from undoing twenty moves to find one mistake.

Habits that help

• Finish small regions first. 1s, 2s and 3s have few possible shapes. Each one you finish adds walls that constrain the large regions later.
• Work from the edges in. A region against the edge or in a corner has fewer directions to grow, so forced moves appear there first.
• Re-scan after every completed region. Completing a region is when new walls appear. Look at every empty cell it touches before moving on.
• Count, don't eyeball. For any region of 5 or more, count the cells it has and the cells it can still reach. Large regions are where mistakes happen.
• Leave the biggest numbers for last. A 9 might look like it can go anywhere. Once everything around it is finished, it usually has exactly one shape left.

Common mistakes

• Letting same-size regions touch. Two separate regions of 3s that share a side are really one region of six 3s. Diagonal contact is fine; side contact never is.
• Assuming every region has a clue. Many puzzles contain regions with no clue at all, often 1s and 2s tucked between larger regions.
• Assuming each clue is its own region. Two clues of the same number can belong to the same region. Two 4s that are close together might be half of one 4-region.
• Guessing. Puzzles in the app with a single solution never require a guess. If you're stuck, look for an enclosed area or a large region with limited room rather than trying a number and hoping.

Getting faster on large grids

On a 16×16 board, scanning the whole grid after every move is slow. Instead, work locally: after each move, check only the regions it touched. Return to a full scan when a local area runs dry. Dragging across several cells to fill a region in one motion saves time too, as does the eraser's drag mode for clearing a mistaken shape.

When you're truly stuck, the hint shows one cell that can be deduced by logic alone. Rather than just filling it in, try to work out why that cell is forced. It's usually a pattern from one of the technique pages that you didn't notice, and spotting it once makes it easier to see next time.

Using the daily puzzle

Each day the app offers a new daily puzzle at three sizes. They are the same for every player, so they're a good way to compare times with friends. Keeping a streak going is also the most reliable way to improve: a few minutes of solving every day does more for your pattern recognition than an occasional long session.