In this game, you are a torpedoman on a World War II U.S. submarine. (There
were no torpedo women during WWII.) The torpedoman typically didn't have to
set the gyro mechanism for each torpedo, as this was done automatically by
the Torpedo Data Computer, or TDC (see Firing Procedure); he just had to
make sure that the settings of the TDC matched those on the torpedo. On this
submarine, though, you have to set the gyro manually.
Your job is to sink the enemy ship before it locates you. Once you launch
your first torpedo, you'll have 120 seconds to sink the enemy ship before it
locates you.