Genre: Arcade      Creation Date: 1988     Language: 6809 Assembly Language     System: Tandy 512K Color Computer 3


With Space Intruders, I decided to go retro. Up until now, all my games have been original concepts derived from elements from other games. This time I have taken the classic arcade game of Space Invaders (actually Space Invaders Part 2) and jazzed up the graphics.

There were many Space Invaders clones for the original Tandy Color Computer over the years but none that I felt were anywhere near as good as the original. There were certainly none written for the new Color Computer 3 at the time and that is probably because Space Invaders was a dated idea. I hoped that by giving the graphics a graphical update, it may give it a new lease of life. Plus, Space Invaders is a simpler game to create and this would give me an opportunity to try some news routines I had been designing for the new Color Computer 3.

Original Story Pretext

"Enemy alien creatures have been identified entering our solar system, their destination, our home planet! Their goal, the total annihilation of our race. They must not be allowed to land!

As you position yourself at the helm of a giant particle beam laser cannon, you sense that sinister rhythm of the Space Intruders as they break through the cloud cover. You immediately unleash the awesome power of your cannon destroying them one by one as they descend towards the planet surface.

Suddenly a report comes to you from control headquarters. A gigantic alien vessel has also entered the solar system. Could it be the Alien Superior?!"

A bloated description that basically says, "Get the buggers before they get you!"   :)

Game Development

In designing the new graphics for Space Intruders, I wanted something that looked contemporary but still retained elements of the classic graphics used in the original arcade masterpiece. The image on the right lets you compare the differences. As you can see, the new enhanced graphics still bare a strong similarity with the original.

Another reason I chose to do a less ambitious game was that I was exploring new ideas for graphics and sound engines. My old graphics engine created all the graphics "offline" in memory and then switched the displayed page to this offline image when a frame was complete. This time, I did everything on one screen. This was also due to the number of moving characters, 55 in all, that would have created a bigger slowdown than what I experienced in Rupert Rythym had I used my old techniques.

I also experimented for the first time with "interrupt driven  routines". The idea was to set up the player's laser base object to be interrupt driven. The main program would only drive the alien invaders, sound and all missiles while a separate subroutine was called up at fixed intervals via a hardware interrupt that would move the player's laser base left and right. It worked very well with the laser base moving silky smooth. I recall a few moments during development when the program would crash and everything on the screen would freeze or corrupt yet the laser base continued to move smoothly left and right across the bottom of the screen. I liked this interrupt driven stuff and I had to find other ways of using them in the future!


The aliens are coming!

Wave 9 - The Mothership!

I did add some extra innovation to the old game of Space Invaders. In the original, you can never win. You are presented with wave after wave of enemy invaders till you finally expire all your laser bases. In Space Intruders, there are 8 waves of progressively harder rounds and in wave 9, the Mother Ship arrives! This part of the game is modelled on arcade "Pheonix" and you are required to penetrate the base of the Mother Ship and eventually shoot the Alien Superior within before the vessel lands and invades Earth. Succeeding this, you actually win the game!

Marketing and Sales

Again, Tandy Australia marketed my game. Again I created a rough sketch of the artwork I wanted and a commercial artist created a final sketch. Tandy allocated a Catalogue Number and I arranged for tapes to be duplicated.

But I saw a disturbing trend. Tandy placed two orders, the first for 200 copies, the second for 100 copies...and that was it. 300 copies only. It was late '88 and I was starting to suspect that the Color Computer was starting to run its round. There was still enthusiasm in the US but here in Australia, it didn't seem so positive.

Understandably, Tandy was promoting their Tandy 1000 range of IBM compatible computers. Higher price tag, larger profit. But to Tandy's credit, they were one of the few manufacturers still selling an 8-bit computer at the time  while the rest of the market had moved on to 16-bit systems such as Commodore Amiga's, Atari ST's, Apple Mac and IBM 286 PC's.

I decided that it was time to make inroads into the US market and I found an opportunity via a new startup company called "Game Point Software". This was a company being run by a nice fellow by the name of Peter Ellison who was at the time selling some game software by the famous CoCo games programmer, Steve Bjork. He was advertising for new games submission to market so I sent copies of my Donut Dilemma (Color Computer version), Rupert Rythym and Space Intruders. He liked them and added them to his product line. He had new game packages made up and ran full page advertisements in "The Rainbow", the largest Color Computer Magazine at the time. My games recieved positive reviews in various Color Computer magazines and sales were reasonable. I don't know the exact number of copies sold because we came to an arrangement of payment via a barter system. He maintained an account of the money collected and I would request things like the purchase of some software or the subscription of certain magazines. I was happy with this arrangement because it made up for the blackout here in Australia of Color Computer products and information about what was going on in the Color Computer world. Sales were nothing like what I had achieved via Tandy Australia but I felt that some sales were better than no sales. Later, Game Point even took on my next project (see next project page), the Rascan Video Digitizer and began selling these.

Click HERE to see a full page advertisement for Game Point games software.

Then, something strange happened. Game Point Software dissappeared! Just closed up shop and vanished. It was very strange because I found Peter Ellison to be very friendly, helpful and honest fellow but something must have happened and he folded overnight and I never heard from him again. Oh well, that's how life is in the fast lane I guess.... and there goes my US link.

Before Game Point Software folded, I was feeling that the end was approaching and I already decided to try something different. I had decided to move into hardware development!