How to play Hide and seek, the Battleships puzzle

The puzzle behind Hide and seek: Battleships

The puzzle grew out of the old two-player guessing game of sinking ships on squared paper, turned into a puzzle you solve on your own by logic. The solitaire version is usually credited to the Argentine puzzle maker Jaime Poniachik and first appeared in the early 1980s. It has since become a regular in puzzle magazines and at puzzle competitions.

Also known as Bimaru, Battleship solitaire, Solitaire battleships.

Hide and seek keeps the classic rules with a garden theme: ships are caterpillars two to four squares long, single-square ships are ladybugs, and water is grass. Smaller gardens have smaller fleets, and 10 by 10 gardens use the classic fleet of ten. A hider placed where nobody hides costs one of three hearts, unless you play in relaxed mode.

How to play Hide and seek

Pip the mouse is it. Find every caterpillar and ladybug hiding in the garden.

• The list by the hearts shows who is hiding: caterpillars two to four squares long, and ladybugs that take one square.
• The numbers count the hidden squares in each row and column.
• Caterpillars lie straight, across or up and down. Hiders never touch, not even at the corners.
• Some pieces are shown at the start, with a little leaf. A caterpillar end shows which way its body goes; a round middle piece can still run either way.
• A hider where nobody hides costs a heart. You have three.
• Find everyone with every heart and no hints for three stars. A hint or two caps the garden at two stars, and lots of hints at one.
• Relaxed mode in the settings has no hearts: it only shows when hiders break a rule.

What you can never do

• Hiders never touch, not even at the corners.
• Caterpillars never bend: they lie straight.

Controls with Pip the mouse

• Tap a square to lay grass where nobody hides. Drag to lay grass on several.
• Double tap, or press and hold, to find a hider. Or pick Find in the tools and tap.
• With a keyboard, use the arrow keys to move, Space to lay grass, Enter to find a hider and Backspace to clear.
• Undo takes back your last move. Hint shows the next step, and why.

Strategies for beginners

Clear the zeros and the full lines

A row or column with a 0 is all grass. So is the rest of any line that already has as many hiders as its number. Lay that grass first: it shrinks the garden for everything else.

Fill the lines with no spare squares

When a line has exactly as many open squares left as its number still needs, every one of them hides someone. This often happens early on small boards and near the edges.

Grass goes around every hider

Hiders never touch, so the four squares at the corners of any hider are always grass. Once a caterpillar or ladybug is complete, every square around it is grass too.

Read the pieces you are given

An end piece shows which way its caterpillar runs, so the next square along is a hider and the square behind it is grass. A ladybug is a whole hider, so grass surrounds it. A round middle piece runs across or up and down, and the squares at its corners are grass either way.

Place the longest caterpillar first

The longest caterpillar fits in only a few places, because it needs a straight run of open squares and enough room in the row or column counts. Find every spot it could lie. If they all share a square, that square hides someone.

Keep count of the fleet

The list by the hearts counts each hider as you find it, so you can see who is still missing. Once every long caterpillar is found, no run of hiders can grow longer than the ones still missing, so close those runs off with grass.

Try a what-if on the hardest gardens

Expert gardens need one. Imagine a hider on a square and follow the counts. If a row, a column or the fleet breaks, that square is grass. Master gardens go one step further, with a what-if inside a what-if.

Quick tips from the game

• A row or column with a 0 is all grass. So is a line that already has all its hiders.
• The squares at the corners of a hider are always grass.
• Look for the longest caterpillar first: it only fits in a few places.
• The hardest gardens can need a what-if: imagine a hider on a square, and if the numbers break, that square is grass.

Words to know

Ship

A hidden piece lying straight across or up and down. In Hide and seek ships are caterpillars, and single-square ships are ladybugs.

Fleet

The full list of ships hiding on the board, by length. Hide and seek shows it by the hearts.

Water

A square where no ship hides. In Hide and seek water is grass, and you can lay it as a note.

Segment

One square of a ship: an end, a middle piece or a whole single-square ship. Some segments are shown at the start.

Row and column counts

The numbers beside the grid. Each says how many squares in that line belong to ships.

Touching

Two ships side by side or corner to corner. It is never allowed, so ships always have water between them.

Questions about Hide and seek