Monthly Archives: February 2018

Jetboard Joust Devlog #80 – Squid’s In!

This latest enemy was inspired by the rockets in ‘Scramble‘, the other seminal side-scrolling shooter (along with ‘Defender‘) that defined the genre for me in the early days and paved the way for the likes of Nemesis, Salamander, Gradius, and all that came after.

I didn’t want to have bog-standard rockets though. Every other enemy in the game is humanoid to a degree (when I do have spaceships etc there’s an obvious humanoid pilot). I feel this imbues them with much more personality – so I began working on ways to ‘humanize’ a rocket.

I was thinking about Tomohiro Nishikado’s original sketches for ‘Space Invaders’, which were in part inspired by aquatic life like jellyfish and crabs, when I hit upon the notion that giant squid are not only very rocket-like in form but also have great Cthulhu overtones which links in to some of the other art in the game (the Mutants in particular).

So I decided to name this enemy a ‘squocket’ – a cross between a squid and a rocket. What I didn’t consider though was how much of a bastard those tentacles would be to animate! The main animation took me the best part of a day and is probably the most fiddly piece of pixel art in the game so far. I’m pleased with the end result though, I decided to make the animation symmetrical because it was simpler and also felt more ‘Space Invaders’ that way.

There’s also an idle animation as the squockets wait for the player to approach. This is much simpler but still took a while finding a nice way to make it loop. In the end I decided on a five frame ‘back and forth’ animation for this.

The movement of the squockets was pretty easy to code – I work out the angle between the squocket and the player and ‘lerp’ towards this. What I was finding was that multiple squockets began to overlap after a while (often almost exactly aligning) which looked pretty daft, so to counter this I started polling the player’s position only around four times a second and adding a certain amount of randomness to the polling time, this has pretty much alleviated the issue though I may work a bit more on this – maybe adding a ‘ram’ attack or something.

I also had to deal with squockets becoming ‘stuck’ on the side of buildings if there was a building between them and the player. To solve this I have the squocket rotate upwards if it hits the left or right of a building and to a horizontal position if it hits the top of a building. This seems to enable them to find their way around pretty well. I did play around with a ‘lookahead’ sprite placed a certain distance in front of the squocket and using this to navigate around buildings but this approach almost worked too well (they would avoid buildings so effectively that the player could hide too easily).

Lastly I gave them the ability to fire (I actually re-use the bullets from the original ‘spreader’ weapon) and added a simple ‘tell’ animation prior to firing.

Dev Time: 2 days
Total Dev Time: approx 162 days

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The Main Squocket Animation

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Squockets At Rest

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Jetboard Joust Devlog #79 – Space Invaders

In my last post I wrote about maybe recycling the old ‘Evil Mother’ enemy into something based on the classic ‘Space Invaders‘ aliens, and that’s exactly what I’ve ended up doing!

I like the idea of including a few homages to the classic arcade shooters of yesteryear in Jetboard Joust, and as ‘Space Invaders’ was really the granddaddy of them all it’s an obvious choice. I wasn’t sure whether the formation/movement of the invaders would work within the horizontal/scrolling format of Jetboard Joust but, with a few tweaks, it actually seemed to work out pretty well.

It wasn’t too tricky to code either. I was worried that get the whole batch of invaders to move together around buildings and stuff would be a pain but it was pretty straightforward in the end.

What I do is move all the invaders as a batch rather than treating them as individual sprites. Collision detections are still handled individually and, when an invader collides with a building, it sends a message back to the batch telling it to change direction. When the batch is initiated I make sure it doesn’t take up more vertical space than the space between the highest building and the top of the screen so I know it’s never going to get stuck.

Probably the trickiest thing was deciding how to treat a batch of invaders when attacked by the ‘Gravity Hammer‘ weapon. Moving the whole batch at once would just look dumb so I needed a way of having individual enemies break formation when hammered and then return to the appropriate position once they recover.

To achieve this I have a property for each invader that stores its location within the batch separate from its position on screen. If the invader is forced to break formation it is relatively simple for it to return to its batch position. Though it wasn’t strictly necessary I also decided to have individual invaders track horizontally with the batch even when hammered (so only their vertical position is displaced). It just seemed to look better this way.

In keeping with the original I have the invader’s speed and rate of fire increase as individual invaders are destroyed.

Dev Time: 1 day
Total Dev Time: approx 160 days

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Admit It – You’ve Always Wanted To Play ‘Space Invaders’ With A Flamethrower!

Using The Plasma Rifle To Dispense With A Batch Of Invaders


Jetboard Joust Devlog #78 – Return of the Evil Mothers

Too long since the last update. Had a lot of shit on – decided to fight a parking ticket issued by one of those fascist private parking companies and it ended up in court. I beat the tossers but it took so much time preparing the defence and everything I’m not sure if it was worth it, just did it on principle really as I don’t like scammers or bullies. Turns out these scumbags didn’t even have the right to operate on the land on which the ticket was issued in the first place!

Anyway, back on topic, the first major ‘new’ enemy is actually an ‘old’ enemy redone, but I don’t think there’s any shame in that. If you’ve been following this for some time you may remember the ‘Evil Mother‘ enemy. Well, I’d come to the conclusion that this enemy just wasn’t big enough and would work better (and make more sense) as some kind of mini mothership that spilled out its occupants when destroyed.

So I spent quite some time designing a kind of ‘bathysphere’ type craft. It’s actually several different sprites in one, the ship itself, the pilot, the ‘antennae’ on the top which acts as a weapon, plus the various lights. I’m pretty pleased with the result though a little worried it looks a bit too ‘2D’ and could do with some more shading or something to make it appear more ’rounded’.

I also increased the size of the enemies that spill out when the craft is destroyed and spent quite some time working on a much improved bullet that tracks the player’s movement in a similar way to the Limpet Mine. There’s also a ‘tell’ that the ship is going to fire as you can see the antennae at the top charging up.

The shaking effect is achieved by applying an offset to the ships position each frame. These offsets are always evenly distributed and chosen at random so it’s a very predictable type of brownian motion.

I think I’m going to use the original enemy design as more of a ‘swarm’ type enemy with a movement type that’s an homage to the original Space Invaders!

Dev Time: 3 days
Total Dev Time: approx 159 days

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Jetboard Joust Devlog #77 – Keeping Your Enemies Close…

Been working on some new jetboarding enemies over the past few days, so around a day of pixel-pushing and a day of coding with the extra half day fixing bugs caused by the new ‘world wrap’ technique I described in my previous post. I’ve also been rejigging my sprite sheets so the art used for the jetboard and weapon attachments is duplicated on the enemy sprite sheet (fewer spritebatch calls to the GPU needed and should also make things easier if/when I add alternate colour palettes).

Fortunately new jetboarding enemies are relatively simple from a code point of view as a much of their ‘personality’ is defined by tweaking parameters already present in the AI. I also have a fairly decent template for doing the animations now too. Here are the new enemies that have been added, names are just codenames really so may well change…

1. The Master Minion
This is really just a bigger, stronger, and slightly more dangerous version of the omnipresent ‘minion’, the game’s cannon fodder. They’re quicker to snatch your babies away and mutate too!

2. The Ninja
Small, fast, light, very aggressive, but also pretty weak. This guy is very dangerous and performs a ‘pincer movement’ around the player really frequently making him a tough opponent to deal with.

3. The Aggressor
This guy is strong, fairly nimble, and very aggressive when you rile him but he’s actually pretty dumb and will let you sneak up behind him and get in the first shot. A bit like some of the knights in ‘Dark Souls’ (well, kind of)! You can tell which way he’s facing by looking at the scanner. This enemy required some custom AI work.

4. The Thug
This guy is very big and strong and takes a lot of ammo to dispatch. He’s pretty slow though, and not the brightest lamp on alien street either. I was particularly pleased with how the art for this one worked out.

5. The Snatcher
All this guy cares about is stealing your babies and trying to mutate. It’s like he’s a kind of half-mutant already and is desperate to finish the job. He’s a bit of a coward and will actively try and avoid the player unless directly engaged – watch him though, as he’ll snatch away your progeny and mutate really quickly if you don’t keep an eye on the scanner! This enemy required the most custom AI work.

This brings the total of enemy types to 12, I think I’m going to try and bring it closer to 20 and want to add some ‘miniboss’ type enemies with much larger sprites. few more smaller ones to do yet though…

Dev Time: 2.5 days
Total Dev Time: approx 156 days

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The Master Minion – Upgraded Cannon-Fodder

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The Ninja – Fast And Dangerous

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The Aggressor – You Won’t Like Him When He’s Angry

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The Thug – Strong But Easily Outwitted

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The Snatcher – A Devious Coward