Samphire Salvo

What is a sea battle game?

The pencil and paper sea battle goes back to the years around the First World War, when it was played with two grids drawn on squared paper. Each player marks a hidden fleet on one grid and uses the other to keep track of shots at the enemy. It has gone by plenty of names since: salvo, broadsides, sea battle, hunt the fleet.

The rules take a minute to learn, but there's real skill in where you fire and where you hide. We built Samphire Salvo so you can enjoy both: a quick, friendly game with satisfying splashes and blasts, and hints that show you the odds on every square. It's free, it runs in your browser and there's nothing to download.

How to play

1. Place your fleet. Drag each ship onto your sea. Ships lie across or down, never diagonally, and can't overlap. Tap a ship to turn it, or roll the dice for a random fleet.
2. Take turns firing. On your turn, pick a square of their waters, like C7. Rows are letters down the side and columns are numbers across the top.
3. Hear the answer. A white peg is a miss. A red peg is a hit. When every square of a ship has been hit it sinks, and you're told which ship it was.
4. Win. The first player to sink the whole enemy fleet wins.

In the classic fleet, on a 10 by 10 sea, each side has a Flagship (5 squares), a Cruiser (4), a Frigate (3), a Submarine (3) and a Patrol boat (2). The quick fleet uses a 7 by 7 sea with four ships, and the big fleet a 12 by 12 sea with seven, adding a Destroyer and a Launch.

Salvo, hit goes again and ships touching

We offer the three ways people most often play. With one shot a turn you simply take turns. In a salvo you fire one shot for every ship you still have afloat, all at once, so every ship you lose costs you firepower. With hit goes again you keep firing for as long as you keep hitting.

You can also choose whether ships may touch. When they can't, every ship needs a square of open water all round it, even at the corners. That makes the hunt more of a puzzle: when you sink a ship we mark the water round it as clear for you, and that water can't hide anything else.

How to find a hidden fleet

Good shooting comes in two parts. While you have nothing to chase you are hunting, spreading shots to find a ship. Once you hit something you are targeting: the rest of that ship is right next to the hit, so work round it, and as soon as you have two hits in a row, follow the line to both ends.

When hunting, fire on a checkerboard. Every ship covers at least two squares, so firing only at every other square (like the dark squares of a chess board) still finds every ship with half the shots. Once the Patrol boat is gone and the smallest ship left is 3 long, you can spread even wider.

Then count the room. A gap of two open squares between misses can't hold a ship of three. Squares in the middle of the sea fit more ways a ship could lie than squares on an edge, which is why counting players start in the middle.

Playing Samphire Salvo

• On a phone or tablet: drag your ships onto the sea, tap one to turn it, then tap a square of their waters to fire. The two seas swap places as turns change, so yours grows while they fire at it. Turn on Tap twice to fire in Settings if you like to be sure.
• With a mouse: drag to place, click a ship to turn it, and click their waters to fire. The sights follow your pointer.
• With a keyboard: Tab to the sea. While placing, the arrow keys move a ship, R turns it and Enter drops it. While firing, the arrows move the sights and Enter fires; in a salvo it adds a square and F fires the lot. H shows a hint, U undoes and Esc opens the menu. Screen readers hear every square by name and every answer.
• Hints and the shot review: the light bulb shows the square with the best odds, with a glow on every square by its chance of hiding a ship. After a game, the shot review points out the shots with the worst odds next to what was on offer.

High contrast mode gives a dark sea, a white grid and bold marks with a cross, and there's a less motion setting for anyone who prefers shots to land without animation.

The house players

Five sea creatures, each a clear step up from the last. We played thousands of games between them to check that each one beats the one below.

The house players never see your fleet. They only see the marks on your sea, the same as you see on theirs.

Daily Fleet and the ladder

Every day brings three hidden fleets, the same for everyone, hidden the way Fathom hides its own. The cove is a 7 by 7 sea with four ships. The open sea is 10 by 10 with five ships that never touch. Far waters is 12 by 12 with seven ships. Sink each fleet in as few shots as you can: a round scores 100 if every shot hits and 0 if it takes every square. Your first go of the day goes on the daily leaderboard, out of 300, and you can share a card that never gives away where the ships were.

The ladder is a rating that starts at 1200 and moves after every game against a house player. Beating a stronger player moves it more. A game where you took a shot back doesn't count. Sign in to keep your ladder, streak, awards and unlocked seas on every device.

Play with a friend

Two can play on one device with pass and play. Each of you places a fleet while the other looks away, and we cover the screen between every turn so nobody sees the other fleet. To play someone far away, open Play a friend, host a game and share the four letter room code or link. The host picks the rules and either of you can ask for a rematch.

Online, your fleet never leaves your device. Each side answers the other's shots itself. At the start each device sends a sealed fingerprint of its fleet that shows nothing, and at the end both fleets are shown and checked against the fingerprints and every answer, so nobody can move a ship halfway through. Online games use preset reactions only, with no typed chat.

Tips and strategy

• Finish what you start. A hit with open squares round it is almost always the best place to fire next.
• Two hits in a row tell you which way a ship lies. Stop firing at its sides and go for the ends.
• When a ship sinks, look at the hits left over. If there are more hits than the sunk ship covers, another ship is lying right alongside.
• Hunt on a checkerboard, and widen the gaps once the small ships are gone.
• When hiding, spread your ships out and don't line them up end to end, so finding one doesn't lead straight to the next.
• In a salvo, spread your shots. Two shots next to each other while hunting waste half their chance.
• In a salvo game your firepower falls with every ship you lose, so protecting your fleet matters as much as hitting theirs.

Questions