MyNumo makes some good games and Torpedoes Away is no exception.  The game instructions say:

In Torpedos Away! your goal is to shoot the red mines with your torpedos.
There are special ‘power-up’ bubbles you can collect for additional lives, protection, and extra points.
If you run into a mine you will lose a life (unless you have the special bubble shield).
Touch the arrows to control the movement of the sub.
You can reverse direction, dive or climb. Launch your torpedos with the ‘FIRE’ button.

Personally, I really liked this game and enjoyed playing it.  The game's very easy and doesn't require you to concentrate too much so it's somewhat relaxing to play.