What this game is
Battleship is not a game about luck, it is a game about information. Every shot, misses included, tells you something new, and the only question is whether you know how to use it.
Your fleet is on the left, the enemy waters on the right, and about them you initially know nothing. Twenty cells out of a hundred hold ships, and hunting for them at random can take a very long time. But ships never touch, every ship's length is known, and a miss marks a cell permanently — the whole strategy grows out of those three facts.
A game is usually decided before the first hit, by how you searched. A good search pattern saves a dozen shots, and a dozen shots here is half the game.
Rules
- Two 10×10 grids: your fleet on the left, enemy waters on the right. Each side has ten ships — one four-deck, two three-deck, three two-deck and four one-deck, twenty cells in all.
- A ship lies along a row or a column and never touches another ship, not even at a corner. There is always at least one cell of water between any two of them.
- Both fleets are placed at random when the game starts. Before your first shot you can reshuffle yours, or lay it out by hand: press "Place manually", click to drop the ship at the head of the queue, click a ship already on the board to pick it back up, use "Rotation" or the R key to turn it, and "Random" to fill in the rest.
- You shoot first. Click a cell of the right-hand grid.
- A miss puts a dot in the cell and passes the turn to the computer. A hit puts a cross there and you shoot again. The turn stays with you as long as you keep hitting.
- A sunk ship is revealed in full, and all the water around it is marked as fired at automatically: by the no-touching rule nothing can be there, so there is no point spending shots on it.
- The first player to sink all ten enemy ships wins. There are no draws in this game.
- The counter on the right shows sunk ships, not hits.
How to play better
- Do not shoot at random, shoot on a net. A ship of length L always covers at least one cell of a net with step L. While the smallest ship afloat is a two-decker, firing at every other cell in a chequerboard pattern covers the whole board with half the shots.
- Hunt the big ships first: they are the easiest to find, and once the four-decker is gone you can tighten the net.
- After a hit, establish the direction. Two hits in a row fix the ship's axis, and from then on only the two cells at the ends of the run are worth anything — a shot sideways is guaranteed to be empty.
- Use the no-touching rule. All four cells diagonally adjacent to a hit are water, and that is certain. Around a sunk ship the game marks the water for you.
- Late in the game stop asking "where have I not shot yet" and start asking "where does the remaining ship still fit". On a well-peppered board a three-decker usually has only two or three possible berths left — shoot there.
- When laying out your own fleet, remember that a probability-counting opponent aims at the centre, because more placements fit there. Against the computer here the edges are the best place there is: it does not remember your past layouts, and a fleet along the sides lasts longest.
A bit of history
Battleship began as a pencil-and-paper game in the early twentieth century. It was drawn in notebooks and pads from around the time of the First World War, and in the 1930s various publishers started selling it as printed pads with the grids ready-made.
In 1967 Milton Bradley released the plastic board version — the briefcase with the upright boards and the little pegs. That is the form in which most of the world knows the game.
The board on this page follows the other, notebook tradition, the one played at a school desk: a 10×10 grid, a fleet of one four-decker, two three-deckers, three two-deckers and four single cells, ships forbidden to touch, and a hit earning another shot. In the Russian interface the columns are lettered А to К.
The program itself follows the Battleship applet that ran on this site from 2005: the same cyan panel, the same old-fashioned menu bar and the same grey flash on a cell before the computer fires.
About the levels
What all three share: the computer sees exactly what you would see in its place — the grid of misses, hits and sunk ships, plus the list of lengths still afloat. It never looks at your layout, on any level. It also places its own fleet at random regardless of the difficulty you pick.
Easy fires at a random unknown cell. After a hit it picks one of its wounded cells at random and shoots a random neighbour of it. It has neither a net nor a sense of direction: even when two hits in a row make the ship's orientation obvious, it may go on poking around at random.
Hard does collect hits into connected runs. A run of two or more gives it the axis and it shoots one of the two ends. While hunting it uses a parity net: only cells whose coordinates add up to a multiple of the smallest ship still afloat. But while a single one-decker is afloat the smallest ship is one cell long and the net is the whole board; it can only thin out at the very end. So in practice it hunts at random: it never works out where a big ship can still fit.
Expert counts probability density. For every ship still afloat it enumerates all of its possible placements, discards the ones that contradict what it knows, and lets each survivor vote for the cells it covers. The shot goes to the cell with the most votes. A placement that explains a wounded deck weighs two hundred times more for each such hit covered — which is what turns the hunt into a chase along the ship's axis with no separate targeting mode at all.
Expert has one weakness, but a genuine one: when it discards impossible placements it looks only at water and sunk ships. It does not apply the no-touching rule around a wounded ship, so it seriously considers placements pressed up against something it has already hit. In practice that costs it almost nothing: the weight on a wounded deck already keeps it from firing beside the ship.