Battleship

Goal of the game

Sink the AI’s five ships before it sinks yours. Each fleet has an aircraft carrier (5 squares), a cruiser (4), a destroyer (3), a submarine (3) and a patrol boat (2).

Placement

• Drag each ship onto your grid. Tap a placed ship to rotate it, or use "Rotate" (R key).
• You can also select a ship from the list, then tap the square where it should go.
• "Random" places the whole fleet in one go. Ships cannot overlap, but they can touch.

Battle

• On your turn, tap a square in the enemy waters (or move the crosshair with the arrow keys, then Enter).
• Miss: no target.
• Hit: a ship has been struck.
• Sunk: all of its squares have been hit; it is then revealed.
• "Fire again on a hit" rule: a successful shot earns you another shot.
• On a phone, the tabs switch between the enemy waters and your fleet; the switch is automatic during the AI’s shot.

Online

Each player keeps their fleet on their own device. Before the battle, each side sends a cryptographic fingerprint (SHA-256) of its layout; at the end, the fleets are revealed and checked, so a false answer is detected. The first shot is drawn at random.

About the AI

The AI never sees your fleet: it only knows the results of its shots and the ships it has sunk. At Master level, it randomly draws thousands of complete fleets compatible with all its observations, weighted so that every possible arrangement counts equally, and aims at the square most often occupied (a Monte Carlo estimate of the probability). At Expert level, it computes a density map: the number of possible positions of each remaining ship that cover each square, with a heavy weight on positions that extend a hit. At Advanced level, it sweeps the sea in a checkerboard pattern, then finishes off damaged ships. At lower levels, its shots are increasingly random. The hint displays the probability map computed for you.