Play Code Name: Sector

What is Code Name: Sector?

(I'll just abbreviate it as CN:S.) CN:S is an HTML5 version of an old computer/board game of the same name. The original CN:S was published by Parker Brothers in 1977. The human player(s) plotted on the game board the positions of four destroyers as they sought out a computer-controlled submarine.

How do you play?

The rules (pdf).

How does this version differ from the original?