World War II. The North Atlantic. The Americans are shipping millions of tons of war materiel to their European alliesevery month-- troops and weapons that pose a grave threat to the Axis war effort.
You are in command of a Type VIIC U-boat, a silent undersea killer. Sailing from the captured French port of Lorient, it is your duty to intercept the Allied convoys and sink as many tons of shipping as possible before they reach port.
Easy difficulty takes place in the summer of 1943, when your supplies were plentiful and Allied escorts were scarce, making for ideal hunting conditions.
But each higher difficulty level takes place later in the war, as your fight becomes more and more desparate. You have fewer torpedoes to work with, armed escorts are protecting almost every convoy, and the deadly Fletcher-class destroyers are showing up more and more often.
A series of walk-throughs to help you learn how to play. You should start here.
A single encounter with a randomly-generated convoy. Could be a single ship; could be a giant fleet! These games usually last between 5 and 20 minutes.
A long patrol of the North Atlantic that presents a series of convoy encounters. You will have to manage your ammo and fuel supplies, with the goal of finding and sinking the maximum tonnage possible before returning to your home port.
Pre-defined single convoy encounters. Everyone can play the exact same configuration and compete on the leaderboards for who can finish the challenge the fastest.
As a hit-and-run stealth hunter, simply surviving is a victory. However, we measure the quality of your win by "tonnage"; that is, the total displacement in tons of all the ships you sank. On a War Patrol, that usually means sinking every transport ship or large warship you encounter, then escaping before the escorts can sink you.
You can also try to sink all the escorts, but you'll wind up expending a lot of precious ammo in exchange for small tonnage gains.
In a convoy encounter, there's really only one way to lose: By allowing your sub to go below its crush depth and implode.
In a War Patrol, you can also lose if you run out of fuel before returning to base. At that point, you have a random chance of being rescued; the closer you are to base, the better your chances.