New 3D Amstrad game: Anaglyph Aliens

19 June 2024

I've written a new listing for the final issue of Amtix CPC magazine, which has just been published. It's a game called Anaglyph Aliens that uses 3D red/blue glasses to make aliens fly out of the screen at you.

I've long held an interest in 3D effects. One of the first articles to go live on this website more than 25 years ago was about stereograms, and my book Cool Scratch Projects in Easy Steps showed you how to make 3D games using Scratch (and included a pair of the glasses).

I was curious about whether it would be possible to create a 3D game for the Amstrad. It all came down to how well the machine's built-in colours matched the lens colours in 3D glasses. While there was some ghosting as a result of colour leakage, the 3D effect worked. I wanted to make sure the game design used the depth as a gameplay element, and not just background scenery, so the aliens fly towards you.

I also wanted the program to make sense as a listing, intended to be read and typed in. In the 90s, listings often had lots of sprite data, which was boring to type in. This wasn't really questioned at the time because there was no other way to get the software, other than buying it on tape which was unviable for most short programs. Now that we can easily download software, there's little appeal in reading or typing in a listing that is unintelligible.

To that end, this listing draws the aliens in BASIC, and then uses a tiny machine code routine to convert them into sprites. I really wish I'd had this idea in the 90s. It would have made Fishtank a more interesting and shorter listing, for a start, even without changing the experience while it was running. Anaglyph Aliens also uses the small machine code routine as music data, so that it's possible to have a (strange) jingle before each game, without needing to type any music data in. (I didn't include this line in the mag version, to save space).

It surprises me when I find myself thinking of a new coding technique on the Amstrad, given I've hardly used the platform for years. It feels like my old programming knowledge from my well-spent teenage coding years is still there, but enhanced by the things I've learned since about user experience and the time I've spent programming in Python and Scratch.

Play Anaglyph Aliens in your browser now, or download the disc. If you don't have a pair of glasses to hand, you can order them cheaply on eBay, or find a pair in Cool Scratch Projects in Easy Steps.

As I said, issue 12 is sadly the final issue of Amtix CPC. For this last issue, I've also written a short history of the CPC seen through the final issues of the major magazines and a Flash Back review of Highway Encounter. Over the last few years, the magazine has published 12 issues, plus an annual, coming to a total of about 750 pages. It's been a joy to read and to write for. Thanks to the publisher Chris, editor Colin, the contributors and the readers for making it happen. If you have any gaps in your collection, back issues are available here.

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