Every player hides five ships in their own harbour basin. Then you take turns guessing: you call a square and you are told whether there is water, whether you hit a ship — or whether you sank it. The first player to put the whole enemy fleet on the bottom wins.
You can play on your own against the computer (against one, two or three of them) or against real people with two, three or four players. A two-player game takes about six to ten minutes.
Your waters are 10 by 10 squares. Columns are A to J, rows are 1 to 10. So a square is called B7: column B, row 7.
What you see is a piece of the Rhine harbour — quay wall, cranes, buoys and water in three depths. The depths are purely decorative; they change nothing.
Together they take up 17 of the 100 squares. Everyone has the same five ships — nobody can buy a stronger fleet.
How: tap a ship on the left, turn it with 🔄 and then tap the square where it should go — the tap sets its left or top end. Tapping a ship that is already in the water picks it up again. If a position is not allowed, the game says so and places nothing.
If you do not feel like shuffling, press 🎲 Place at random — that puts down a legal fleet in one go, and you can still move single ships afterwards. There is no time limit: nobody is rushed.
Only ✅ Done sends your fleet off. After that it cannot be moved any more.
On a phone the squares are small, so it takes two steps: the first tap sets a crosshair, a second tap on the same square fires. You can also press the big button that shows the coordinate (“🎯 Fire at D7”). That way a swipe can never fire by accident.
There are three answers:
Nobody can fire at the same square twice — not even at water.
With two players: whoever hits fires again — and keeps firing as long as they keep hitting. A good run can decide a game very quickly.
With three or four players this does not apply. There the next player is up after every single shot. Otherwise one run could knock a player out in a single turn while everyone else just watched.
Everyone has their own basin. Whoever is up picks the opponent first, then the square: the other players sit at the top as tabs with the number of their remaining ships. Tap one to see their waters.
Whoever has no ships left is out. The rest keep playing until one player is left — that player wins. Nobody can fire at the waters of a player who is out.
If you are out you can keep watching and you stay in the room for the next round.
On your own you play the computer at three strengths:
The computer does not look at your fleet. It sees exactly what you see: where shots went and what came of them.
In multiplayer games the server holds every fleet, not your browser. It checks every placement (length, edge, overlap, spacing) and every shot (is it your turn, does the square exist, has it been fired at already). All your browser ever receives is: your own fleet, every shot — and enemy ships only once they have been sunk.
An enemy ship that is still afloat never leaves the server. Even looking inside your browser will not find it.
Pick two, three or four at the top. You land in the lobby and see who is waiting. You can join someone, wait yourself, or have the computer fill the empty seats — by hand right away, or automatically after ten minutes. That way a round always comes together.
All guest seats may be taken at that moment. You can then queue, come back later — or simply play the computer on your own. That always works.
If a player goes quiet for 90 seconds, the game asks the others: “the computer takes their seat” or “new game”. For whoever left, the game counts as lost.
So a short loss of signal is no disaster: come back before the others decide and you simply carry on — the game sits on the server, you can even switch device.
Against real people a win is worth 10 points and taking part is worth 1. They count towards the weekly, monthly and yearly tables. Games in which only computers took part give nothing — otherwise the easiest setting would be the fastest way to the top.
With three or four players second place counts too: whoever held out longest after the winner gets 4 points. The order follows the sinkings — the fleet that went down last comes second. Anyone who resigns always comes last.
Your badges also count games against other players. There are five: your first game against another player, your first win against another player, playing against 3 different people, 5 wins and 25 wins against other players. Every badge is one level.
Practice against the computer does not count towards points or badges. It is not lost, though: your record keeps it separately so you can see how much you have practised.
Whatever level and points you had before 19 August 2026 stay exactly as they were — nothing is recalculated.
The idea is more than a hundred years old and comes from the classic paper game: two squared sheets, a pencil, and you call out squares to each other. The rules, the artwork and the computer opponent here are written from scratch.