Sea Battle

How to play sea battle online

1. Open the Fleet select and choose Classic fleet (default) or Russian fleet.
2. Open the Computer select and choose Computer: easy, Computer: normal (default) or Computer: hard.
3. Keep the random fleet, or place your own. Tap or click a ship in the list to pick it up, then tap or click a cell. The ship’s first end goes on that cell and it extends right or down. The next unplaced ship is picked for you.
4. To turn the picked ship, press Rotate or R. Press Random for a new legal fleet, or Clear to remove all ships.
5. When every ship is placed, press Start.
6. Tap or click a square on “Enemy waters”. A white dot is a miss, a red marker with a cross is a hit, and a sunk ship is outlined in red and darkened.
7. Wait a moment for the computer’s reply. Its last shot is outlined in gold on your grid.
8. When the game ends, the result box shows your shots and accuracy. Choose Play again or Close.

On narrow screens, switch between the “Enemy waters” and “Your fleet” tabs. On a keyboard, move the cursor with the arrow keys and press Enter or Space to fire or place. Press N for a new game, F for fullscreen, and Esc to close the result box or leave fullscreen. There is no Undo and no Hint. To replay the same fleets, add ?seed=123 to the page address.

What are the sea battle rules?

Each side has a fleet hidden on a 10 x 10 grid, and you fire first. The aim is to sink every enemy ship before the computer sinks yours. The classic fleet has five ships: a carrier of 5, a cruiser of 4, a destroyer of 3, a submarine of 3 and a patrol boat of 2, covering 17 cells. The Russian fleet has one ship of 4, two of 3, three of 2 and four of 1, covering 20 cells. Its ships never touch, not even diagonally.

With the classic fleet, the “Ships may touch” option sets the placement rule. At Yes, ships may sit side by side, and only overlapping is forbidden. At No, no two ships may share an edge or a corner. The “After a hit” option sets the turn order. With Take turns, the turn passes after every shot. With Shoot again, a hit or a sinking lets the same side fire again, and a miss passes the turn. Choosing the Russian fleet switches After a hit to Shoot again; you can change it back in Rules. Changing any setting starts a new game with a new placement.

You win when every enemy ship is sunk. The computer wins when it sinks your fleet, and then the enemy ships you never found are revealed in gold.

Sea battle strategy: how does the computer find your ships?

The three levels differ in how they choose a square. Easy fires at a random square it has not fired at yet. Across 30 games with the same classic fleets, it needed an average of 95.2 shots to sink all five ships. Normal hunts at random until it hits, then fires at the four neighbours of the hit. Once two hits line up, it extends that line at both ends. It averaged 64.6 shots. Hard uses the same targeting, but for every square it counts how many positions the remaining enemy ships could still fill, given the misses and sunk ships. It fires at the square with the highest count, which favours a checkerboard-like search. It averaged 44.6 shots.

You can use the same ideas. After a hit, try the neighbours, then keep going in the direction that is already hitting. When ships may not touch, a small faint dot marks water next to a sunk ship. No ship can be there, so firing at it wastes a shot. The computer never fires at those squares. Your accuracy counts only your own shots, as hits divided by shots, rounded to a whole percent.

Frequently asked questions

Is sea battle free, and do I need to sign up?

Yes, the game is free to play on this page. There is no sign-up step: the fleet is placed for you, and you press Start to begin.

Can I play sea battle on a phone?

Yes. On narrow screens the grid is shown alone, with “Enemy waters” and “Your fleet” tabs. A red dot on “Your fleet” means the computer has fired since you last looked. You place ships by tapping the list and then a cell.

Is my game saved?

Yes. The battle in progress is saved in your browser after every shot, so reloading resumes it. Your fleet choice, level and rules are also remembered. Everything stays on this device only, and nothing is sent anywhere. Your placement in progress is not saved, so a reload gives a fresh random fleet.

Can I play sea battle against another person?

No. The game is for one player against the computer. There is no online play and no two-player mode.

Who fires first in sea battle?

You do. The game does not offer a choice of who starts.

Can I undo a shot or get a hint?

No. There is no Undo and no Hint, so each shot counts once.

Is there a timer or sound?

No. The game has no timer, no scoring points and no sound. It tracks won and played games for each computer level, plus your best accuracy in a won game.

More games

• Minesweeper: use it if you like finding hidden things on a grid by logic.
• Gomoku: use it for a strategy game of getting five stones in a row against the computer or a friend.
• Dots and Boxes: use it for a pencil-and-paper style game of drawing lines to claim boxes.
• Tic Tac Toe: use it for a short, quick game on a small grid.
• Reversi: use it for a board game of flipping pieces to take the most squares.
• Backgammon: use it for a dice and race game played on a board.