Original source downloaded [from Vintage Basic](http://www.vintage-basic.net/games.html)

Conversion to [Perl](https://www.perl.org/)

This Perl script is a port of orbit, which is the 68th entry in Basic
Computer Games.

In this game you are a planetary defense gunner trying to shoot down a
cloaked Romulan ship before it can escape.

This is pretty much a straight port of the BASIC into idiomatic Perl.