Exocet

A group of enemy ships randomly make their way across the horizon, and it's up to you to sink as many of them as possible by firing missiles using the space bar. A mobile sight is printed slightly below the line of the horizon. There are three sizes of enemy ships, and the smaller the target the more points you gain. Occasionally the enemy's electronic defense system will succeed in confusing your missile and deflecting it from its course.

From the book "Sixty Programs for the Commodore 64".