How to play Sea Battle (Battleship)

Sea Battle — the classic game most people know as Battleship — is a game of hidden fleets and deduction. You play it here against a computer opponent, with no download and no sign-up. There are two grids on the screen, each ten squares across and ten squares down. The grid on one side holds your own fleet; the grid on the other side is the enemy's waters, where five enemy ships lie hidden under fog. Your job is to find and sink every enemy ship before the computer sinks yours.

The fleet

Each side commands five ships of different lengths: a five-square Carrier, a four-square Battleship, a three-square Cruiser, a three-square Submarine, and a two-square Destroyer. Every ship sits in a straight line, laid either horizontally or vertically, and no two ships overlap. Both fleets are placed automatically at random when a game begins, so you can jump straight in. Before you start firing you can press Randomize as many times as you like to re-roll the layout of your own fleet, then press Start to begin the battle. (Hand-placing your ships by dragging is planned for a future version.)

Firing

You and the computer take turns firing shots. To fire, tap or click an un-fired square on the enemy grid. A small dot marks a miss — open water — while a bright marker shows a hit on a hidden ship. The enemy grid stays fogged: you never see an enemy ship until you have struck every one of its squares, at which point the whole ship is revealed as sunk and a message tells you which ship went down. Your own grid shows your ships from the start, along with every shot the computer has taken at you.

A hit lets you fire again

This version uses the popular "extra turn" rule: a hit lets you fire again, so a good salvo can chain into several shots in a row. A miss ends your turn and passes the initiative to the computer, which fires under the same rule. Pressing your advantage after a hit — and finishing off a wounded ship before the enemy can rebuild — is the heart of the game.

The enemy's tactics

The computer plays a hunt-and-target strategy, the same approach a sharp human uses. While hunting it spreads its fire across the board on a checkerboard pattern, the most efficient way to stumble onto a ship. The moment it lands a hit it switches to targeting: it probes the squares next to the hit, and once it has two hits in a line it follows that line in both directions until the ship is sunk, then goes back to hunting. To beat it, scatter your own fleet, finish ships quickly, and make the most of every extra shot a hit hands you. The first commander to sink all five of the opponent's ships wins. Press N for a new game or R to re-roll your fleet before you start.