Raptor was written by Cygnus, and it seems to be a birthday present to
themselves.  Whenever Raptor is started when your system's clock matches the
birthday of one of the people at Cygnus, Raptor behaves a little strangely.
Here's the list of recognized birthdays.  You can reset your system clock
to one of these dates manually, if you wish; any year should be all right,
so long as it's not in the past:

                       March 12        Bobby Prince
                       May 16          Scott Host
                       August 28       Rich Fleider
                       October 2       Jim Molinets

Note that in v1.0 of Raptor, Bobby Prince's birthday was not recognized,
while Tim Neveu's was.

What happens is this:  first, the Apogee logo is displayed, but not with
Apogee's trademark music.  Instead, you hear the Cygnus folks, sounding a
little tipsy, humming the Apogee theme music themselves.  In version 1.1 and
1.2, Bobby Prince says, "You boys just don't get it, do ya?" immediately
afterward.  (This file is available online in WAV format; the direct URL is
http://www.3drealms.com/sounds/rapgoof.wav.  You'll also hear it if you go to
the Raptor product catalog entry in Apogee's web site and click on the cursor
in Raptor's main menu.)  In addition, some of the Raptor levels contain
enemies that don't normally appear such as monkeys who throw coconuts at you,
raptor dinosaurs scurrying across the screen, and cows with machine guns
concealed beneath their hides.  Most of these peculiar enemies appear on the
first mission of the game, and they are usually difficult to kill.

Finally, when you exit the game, you get to hear the member of Cygnus whose
birthday it is give an impersonation of a monkey.  This might consist of
hooting or screeching sounds, or simply an eloquent rendering of the word
"monkey."  (The raucous you hear when monkeys appear during the game are
all the monkey impersonations playing together at random.)

There is a way, beyond setting the system time to a particular birthday, of
getting the monkeys and raptors and cows to fight you.  When the screen comes
up where you must choose a sector to fly, flip the switch at the bottom center
of the screen by clicking on it with the mouse.  It should darken.  This
activates the three lights to the right of this switch.  In version 1.0 of
Raptor, you should turn on the first and third lights; in v1.1 and v1.2 of
Raptor, you should turn all three lights on.  Then you can select a sector or
"auto pilot" and fly the level.  You'll know the cheat worked if you hear a
static-like sound.  All levels have some new enemy that appears by using this
cheat, though sometimes they are small and inconspicuous.  Besides monkeys,
cows, and raptors, there are:  the ship from 2001: A Space Odyssey, the ship
from Space 1999, pedestrians, a woman sunbathing on a roof, and other
miscellaneous items.

Note, however, that if you activate the "battle cow" mode using the switches,
as opposed to running the game on a Cygnus birthday, you don't get the goofy
Apogee theme song in the beginning, nor the individual monkey impersonation
at the end.