Tag Archives: zx spectrum

Jetboard Joust Devlog #96 – Splitting Up!

Bit fed up with parameter tweaking, so before I finish the final first round of config by going through the treasure chamber guardians and bosses I thought I’d try and get the final non-jetboarding enemies wrapped up.

There’s going to be three of them in all I think, and I’m pretty keen to have each of them be a mini-homage to a classic arcade game, much like of already included one to Space Invaders. First up is Asteroids and an enemy I’m tentatively calling the ‘splitter’.

Originally I had imagined this enemy being a kind of giant jellyfish that split into smaller versions of itself when attacked, but then I happened across the first Starship Troopers movie whilst late-night channel surfing one evening.

It’s a pretty good movie and I haven’t seen it for ages so I ended up sticking with it to the end, and whilst watching it occurred to me that the theme of humans battling off waves of attacks from an insectoid alien race (often with fairly ‘conventional’ weaponry) wasn’t too far removed from Jetboard Joust!

I also thought that the gelatinous ‘brain bug’ at the end of the movie would work very well as an enemy that could split into smaller versions of itself so I used this as the inspiration behind my designs for the ‘splitter’. I drew inspiration partly from the movie and partly from an illustration I found from a 1970s board game version of the book which was simpler and more comic-like.

Rather than try and draw the entire enemy as one piece of art I wanted to build it from smaller components so I could easily make versions at different sizes. First off I created a pulsing body. I tried a number of different versions of this and ended up using a variation of the segments from the ‘squirmer‘ boss. The segments all pulse at the same rate with but start from a randomised offset.

I then added a series of eyes based on the eyes from the ‘spinner‘ boss and a mouth based on the mouth from the mini worms that the ‘squirmer’ gives birth to. It took a while to get the placement of the eyes right, the end result heavily references the movie ‘brain bug’.

Once I was happy with the general placement of the eyes and mouth I needed to make them feel part of the pulsing body as, when simply placed statically they looked far too ‘stuck on’.

I ended up linking each facial feature with a body segment and changing the location of that feature based on the current scale of that segment. This seemed to work pretty well in giving the impression that the features and body were joined rather than overlaid layers.

Enemy movement, as in Asteroids, is very straightforward as – a simple linear motion with a reflective bounce when an obstruction is hit. What was slightly tricky was deciding what to do when the enemy left the camera area. Originally I had it wrapping immediately to the other side of the camera (true to Asteroids). This was kind of cool, and I really liked the fact it was true to its roots, but unfortunately it made the gameplay way too intense – particularly when other enemies were encountered at the same time. I didn’t like the way it made the scanner look broken either.

So I tried simply having them wrap when they reach the edge of the game ‘world’ but this wasn’t intense enough and kind of dull. Eventually I settled on a halfway house between the two, if the enemies are offscreen or nearing the edge of the screen a decision is made as to whether the quickest route to the player is to travel in the same direction or to reverse direction (I take world wrapping and the current player velocity into account). The enemy switches direction (or not) based on this. This keeps the gameplay intense as things tend to cluster round the player but it still makes sense within the overall gameplay paradigm – and it doesn’t make the scanner look like it’s broken.

Something else I’ve been doing which has taken up at least a day of this dev time is working on a ZX Spectrum themed palette and improving some of my palette code. I can now have three different palettes for enemies as opposed to just one. Whilst doing this I discovered some bugs in my palette shaders which were particularly apparent when dealing with 100% RGB values as are used in some of these retro palettes, these are now fixed.

Dev Time: 4 days
Total Dev Time: approx 251.5 days

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mockup_3x
The Brain Bug from the 1970s Starship Troopers Board Game

mockup_3x
The Final ‘Splitter’ Design

Asteroids-Style Wrap Logic – Too Much Mayhem / Broken Scanner!


The Final ‘Splitter’ Alongside Other Enemies – ZX Spectrum Palette