Salvo

Put your four ships on your own grid, then take turns firing at squares on theirs. You are told hit or miss, and a ship is sunk when every one of its squares has been hit. Sink all four of theirs before they sink yours. Play someone next to you and pass the device over, or play the computer.

You each get a 7x7 square of sea and four ships to hide in it: one four squares long, two three long, and one two long. Ships can lie across or up and down, and they are allowed to touch each other. They cannot stick off the edge or sit on top of one another.

To put a ship out, tap it in the list, then tap the square you want its front end in. Tap that same square again and the ship turns the other way. If you would rather not think about it, Shuffle my fleet puts all four out for you.

Then you take turns firing. Tap one square on the other player's sea and you are told what happened: a miss, a hit, or a whole ship sunk. One square per turn, hit or miss. When every square of a ship has been hit, that ship goes down and both of you can see it. Sink all four of theirs and you win.

Two players: the screen goes blank every time the device changes hands, and stays blank until the next player says they are ready. Nobody can see anybody else's ships, which is the whole game - so hand it over properly and no looking.

On your own: the computer hides its own four ships and fires back. It is not guessing at random. It only tries every other square while it is looking, because the smallest ship is two squares long and so it has to be sitting on one of them - and the moment it hits something it works its way along until that ship is sunk.

The trick worth knowing is the same one the computer uses: while you are hunting, skip every other square. You cover twice the sea for the same number of shots and you cannot miss a ship by doing it. Save the careful shots for after you have found something.

Touch: tap anything on the board to use it. Every button and key is at least 44px tall, so it works with a thumb. The squares of a board are as big as the screen allows - on a small phone some of them are smaller than that, which is why the keys and the number pad, not the squares, are what you type with.

Keyboard: Tab moves between the controls and Enter or Space activates the one you are on. That covers the buttons the game screen always has - Pause, Restart and this page's link - as well as anything the board adds.

Pause stops the clock and freezes the board; Restart gives you a fresh one. Both players use the same device, taking turns - whose turn it is is always named on screen.

Your score is how many moves you take. Fewer is better.

Play as often as you like. Every game is saved on this device, and your best turns up on the scoreboard.