Halloween Harry was written by SubZero Software, located in Australia.
Apogee is the game's distributor.  In October of 1993, Apogee released
v1.1 of Halloween Harry in the United States.

As with Wacky Wheels and Mystic Towers, version 1.0 of Halloween Harry was
actually an incomplete version of the game released to a magazine in the UK.
The first complete, public release of Halloween Harry was version 1.1.

A month later, v1.2 of the game was released.  A year after that, Apogee
suggested a title change to "Alien Carnage."  SubZero agreed.  Thus, in
early November of 1994, "Halloween Harry" was dropped from Apogee's
distribution, and "Alien Carnage" added.  Alien Carnage v1.0 is essentially
Halloween Harry v1.2 with a name change, price change, and episode
reorganization.  The shareware version of Alien Carnage (its first episode)
is Halloween Harry's episode three.  With the exception of this
reorganization, Alien Carnage consists of the same episodes as Halloween
Harry.  The shareware version of Halloween Harry is still legal to
distribute; however, Apogee prefers you distribute the shareware version of
Alien Carnage only, as this version has the new pricing information
screens.

In late 1996, Gee Whiz! Entertainment published a sequel called "Zombie Wars."
A demo version of this was released to the Internet.  Apogee has nothing to
do with this sequel, however, and you cannot purchase the full version from
them.

By 1999, Gee Whiz! Entertainment was pulling out all the stops with the
franchise.  "Halloween Harry 3D" was in production, and efforts were made
to develop "Zombie Wars" into an animated television series.  Again, Apogee
has nothing to do with Zombie Wars, Halloween Harry 3D, or the projected
television series.

On April 21, 2000, Alien Carnage was discontinued by Apogee due to technical
problems with the increasing speed of computer hardware.