Xerra's Blog

Drunken coder ramblings

Envahi – Day one —

Tuesday January 30th, 2018

Boulderdash – as close as it is to completion – is going on hold today as I’ve decided to enter a competition to code a small game based on either a TV or Movie theme. This competition is being run by the Syntax Bomb website which is frequented by a lot of ex-Blitz programmers who moved on to other things.

The competition gives you 10 weeks to get your game completed and up onto the site where there is two weeks of judging before the winning three games are chosen. I love the idea of a deadline in this case because I need to push myself to get a game nailed down and this will do it. I’ll be back to finish the current project after April the 10th and I think a break from it is probably going to do me good right now anyway.

So, I gave it some thought with the competition rules, and am going with the theme of Airwolf the TV series and Dambusters the movie. This is because I’ve been itching to do a remake of one of my favourite Vic 20 games which has elements of both. I’ll go with Airwolf as the topic because I like the music and want to use a remix for the game, if I can get a decent version and permission to use it.

First things first was to get a basic framework together before I start actually coding it. When I define start it’s getting the project together, putting all the assets in place and going through previous projects to see what I can pull out to use in the new game.

Envahi is a remake of a Vic 20 game I bought and played in the early eighties. It’s not particularly well remembered, judging by the lack of solid information about it via Google, but I had only just got my machine back then and this was one of the best Vic 20 games for me. As this game is a remake, the basic game design is already there. I don’t want to really do much to change it too much so I don’t really need to plan too much apart from different screen sizing, what elements I want to carry over and where I’m going to get them from. Or if I can get away with coder art here – bearing in mind it’s a competition so would be judged on that.

The original Envahi was probably knocked up using VicMon or a very simple assembler back then – a credit to the author for what he actually got out of the Vic in 8k. Luckily, in this day and age, we don’t even have to think of issues like that, and I’ll be putting it altogether in GameMaker 2.

So what’s the game about? Envahi is a static screen shoot’em up where you have a helicopter that you are flying to try and defend a damn from aliens that are crossing the screen trying to take chunks out of it. I think there’s an element of Cosmic Jailbreak (another classic Vic 20 game) in there – possibly the author, Jeremy Walker, had played that game and was influenced by it. The damn naturally is protecting the city below from getting very wet should the wall get breached.

Luckily it takes 3 bites out of any section of the wall before the water can escape but if it does then it will flood down out of the damn and drown the city.

No pressure then…

As well as the Nibblers attempting to take chunks out of the dam you also had other aliens out to try and get you out of the way so they could destroy the city.

Grabbers – these drop straight down the screen to get to your y-axis and then move horizontally to your position. If you don’t go up or down pronto then you’re lifted off the screen and the dam is left unprotected until the nibblers breach it.

Droppers move slowly down the screen and randomly left or right. They are pretty simple to take out as long as you can avoid everything else happening while you do it. Your helicopter is hindered by only having the ability to shoot up so some pretty deft movement is required.

Clouds appear randomly in the top-center of the screen and start dropping acid rain which will screw your helicopter electrics up and destroy it. You can shoot them but you’re going to have to be pretty dexterous to do this while avoiding the acid.

UFO will go left and right across the top of the screen creating droppers with some kind of regularity based on how long the player has been playing so the game gets harder.

Nibblers are the little buggers that move from right to left trying to bite chunks out of the Dam.

Zoomers are enemies that ignore the dam and just move left and right while moving down a line at a time when they reach the end of each x axis. Kind of like Space Invaders do. However, these are a lot faster and are murderous to take down in the original game.

There should be enough there to keep anyone who plays it busy.

So, because we’re dealing with an already set game plan, I just need to convert it. This actually makes it easier, apart from getting a difficulty balance right, because, just like my last remake, Boulderdash, I’m copying what someone else has done. And then just modifying parts that I think could work better if done a bit differently – although I don’t think I’ll be doing too much of that as the original was so good.

One idea I have had to mix it up is to change how the helicopter is affected by the acid rain from the cloud. The original game just destroyed the helicopter if you hit it but I’m thinking some kind of energy shield system could make it a bit more interesting as tactically you may need to get through that cloud in a hurry. Like if a nibbler is about to take a third chunk out of a wall segment, for example. I’ll decide on this when i implement the clouds and collision but plan for it now when considering the layout of scores and lives data, just in case.

So today’s job was to get the project up and running and get as far ahead with the assets so that it will be mostly about the code going forward after today. I have mostly achieved this which can be seen by first screenshots further down the page. I have most of my sprites in place, the tiles for the water effect (not working correctly but it’s there), some of the sounds ripped out of the original game, a mocked up city built up of public domain building sprites and my helicopter is in place ready for battle. I also did a logo for the title screen, got the image in place there of the big helicopter I already planned to use and animate then finally the basic framework of the project. This means all my slap-dash Boulderdash code has been dumped into the correct object, scripts moved over and basic title to game to title transition in place.

In my head I’ve already mapped out how both the title sequence is going to go so I’ve got extra images for that. I plan on having some bullet holes mark the helicopter with appropriate sounds before the title screen music kicks in. I have the original jingle from the Vic 20 ripped out but I’ll just have that play once on game over or something as a tribute because it can get pretty annoying.

I’m sure posts on this project will be just as spread out as the previous because my working time tends to vary wildly due to work and other commitments but Envhi isn’t a game that should take long. It will certainly be nice to see this one take shape a lot quicker as it’s now my third game using the GMS2 development system.


Categorised as: Competition | Development | Envahi | Game Studio 2 | Syntax Bomb

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