W / S: engine faster / slower (and reverse) · A / D: steer
Mouse: look and aim. Your guns turn towards the circle in the middle of the screen; it goes green when they are ready.
Left click (hold): fire the guns · Right click or Space: launch torpedoes · 1 (or the middle mouse button): guided missile · Wheel: zoom · Esc: pause

Shells fly in an arc and take a moment to land: aim ahead of a moving ship. Guns can't turn through your own ship, so show your side to fire all of them.

A ship is heavy, as at sea: it takes time to pick up speed, and keeps going long after the engine stops (put the engine astern to stop sooner). The rudder needs a moment to bite, a hard turn costs speed, and a ship that isn't moving can't turn. A badly holed ship is slower and leans over. A far gun is seen before it is heard.

On the title screen you choose your ship. The Cruiser has the most guns, launches four missiles at a time, and has anti-missile guns that shoot down most missiles fired at it. The Submarine dives with Shift (press it again to come up): under the water shells and missiles can't hit it, its gun doesn't work there, but its torpedoes and its missiles do. It launches four heavy missiles at a time, each nearly twice as strong as another ship's. Its air lasts 3 minutes. 3 launches its nuclear missile: it follows a ship like the others, and its blast wrecks every enemy ship near where it lands. It takes a minute to make ready again. The Hovercraft is very fast, and torpedoes pass under it. The Carrier launches three jets with 2, and you fly the leader yourself: it goes where you look, and the other two fly beside it. Left click fires all their guns and 1 a missile, one from each jet. They fly for about 45 seconds, or press 2 to bring them back; the carrier sails straight on meanwhile. The carrier has anti-missile guns like the Cruiser's: they fire by themselves, even while you are flying. The jets can't be upgraded. With the Carrier chosen you also pick its jets: F-16, F-18, F-14, F-22 Raptor, F-35 or Su-20. Each has two guns and one missile; they differ in speed, how tightly they turn, how long they fly and how hard their guns hit.

The guided missile follows the enemy ship nearest to where you are aiming, even if that ship turns. It takes 14 seconds to reload, and an island in the way stops it. Enemy cruisers and destroyers have anti-missile guns too, so some of your missiles are shot down on the way in, and they launch four missiles of their own at you now and then.

Torpedoes are slow and strong. Watch for the white trails of enemy torpedoes and steer away.

After each wave your ship is repaired a little and you choose one upgrade. Green crates left by sunk ships repair your hull.

The Carrier sails with two small escort ships, one on each side. They keep their places by themselves and fight the nearest enemy with two guns, two torpedoes and two missiles each; a sunk escort is replaced when the next wave begins. The Hovercraft does 75 knots and carries two armoured vehicles: come close to an island's beach and press 2 to land one. It stays there and fires on enemy ships that come near. More vehicles come aboard with each wave.

Multiplayer (on the website): one player hosts and gets a code in the waiting room, gives it to the others, and presses Start when everyone has joined (players can still join later). You fight the enemy waves as one fleet; more players bring more enemies. If your ship sinks you get a new one when the next wave begins, and the game ends only when every ship is sunk at once.

On a phone: left thumb steers and sets the engine, right thumb looks, and the buttons fire.