Sea Battle

How to play Sea Battle

Sea Battle is a classic two-fleet guessing game of hidden ships and deduction, played on paper for generations before it ever reached a screen. You and the computer each command a fleet on your own secret 10×10 grid. First you position your ships wherever you like, then you take turns calling out squares and firing at the ocean you cannot see. Every shot comes back as a hit or a miss, and from that trickle of information you slowly map the enemy fleet and close in. The player who sinks every one of the opponent’s ships first wins. It takes a minute to learn, rewards careful thinking, and runs entirely on your device — challenge the computer at three difficulty levels and earn ranking points for every win.

The goal

Be the first to sink the enemy’s entire fleet. Both sides start with the same five ships hidden on a 10×10 grid. You can only see your own ships; the enemy grid stays under a fog of war until your shots reveal it. Each ship is sunk when every one of its cells has been hit, and the game ends the instant one fleet is completely destroyed.

The grids and the fleet

Each player has a 10×10 grid — ten columns (A–J) and ten rows (1–10), one hundred squares in all. Your fleet is five ships of different lengths: a Carrier of 5 cells, a Warship of 4, a Cruiser of 3, a Submarine of 3 and a Patrol Boat of 2 — seventeen ship cells in total. Ships sit horizontally or vertically along the grid lines and never overlap. During play you see two boards: your own fleet, with incoming enemy shots marked, and the enemy waters, where you place your own shots.

Placing your ships

• Place each ship by tapping a square on your grid; the ship extends from there in the current direction. A green preview means the spot is legal, a red preview means it runs off the board or crosses another ship.
• Use the Rotate button to switch a ship between lying across (horizontal) and down (vertical) before you drop it. You can Clear the whole layout and start again at any time before the match begins.
• In a hurry? Tap Random to auto-place your entire fleet in a valid layout, then adjust or just hit Ready. The computer always arranges its own fleet secretly and at random.

Rules of play

• Once both fleets are placed, players alternate turns. On your turn you fire at exactly one square of the enemy grid that you have not fired at before — tap the square to shoot.
• Each shot is a hit or a miss. A hit means one of the enemy’s ship cells is under that square; a miss means open water. Hits are marked with a red peg, misses with a white one, so you never lose track of where you have already fired.
• A ship is sunk only when all of its cells have been hit — a 3-cell Cruiser needs three separate hits. When a ship goes down it is revealed on the grid, and the ships-remaining counter drops.
• Turns pass one shot at a time, whether you hit or miss. You never see the enemy’s layout in advance; you learn it only from the hits and misses your own shots produce.

Winning and losing

The game ends the moment one side has sunk all five of the other’s ships. If you finish off the computer’s last ship first, you win and the victory banner appears; if the computer sinks your fleet first, you lose. There are no draws — someone’s fleet always goes down first. Because every hit is permanent and ships never move once the shooting starts, a game usually resolves in well under a hundred shots. Start a New Game at any time to pick a fresh difficulty and lay out a new fleet.

Playing the computer (ranked)

You choose one of three difficulty levels, and they change how cleverly the computer hunts. Easy fires at random squares, so a careful player wins comfortably. Normal uses a hunt-and-target method: it fires randomly until it scores a hit, then works outward to the neighbouring squares to finish the wounded ship before returning to the hunt. Expert adds probability-density targeting — for every square it estimates how many ways the remaining enemy ships could still fit, favours the busiest squares, uses a checkerboard search to save shots, and pursues damaged ships relentlessly. Crucially, the computer never cheats: at every level it decides where to shoot using only the hits and misses it has legitimately received, exactly the information you have about its fleet. It cannot see where your ships are. Everything runs on your device, so it works offline. Beat it to earn ranking points — Easy +10, Normal +30, Expert +100 — and sign in to record your best on the leaderboard.

Strategy tips

• Spread your ships out and avoid the edges and corners as your only hiding spots. Clumped ships are easy to mop up once one is found, and predictable placements are the first the computer clears.
• When you score a hit, stop hunting and start targeting. Fire at the four squares next to the hit; as soon as a second hit lines up with the first, keep firing along that line until the ship sinks.
• Search efficiently with a checkerboard pattern. Because the smallest ship covers two cells, firing only on same-coloured squares of a checkerboard still touches every ship, and finds them in roughly half the shots.
• Count what is left. The ships-remaining counter and the sizes you have already sunk tell you which ship lengths are still out there, so you can stop probing gaps too small to hold any surviving ship.

Frequently asked questions