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  • A Dark Intelligence: Part 1

    [06.13.13]
    - Mike Hanson
  • [PowerUp developer Mike Hanson offers tips on how to create compelling enemy characters, detailing the "Dark Intelligence" that promotes difficulty and challenge.]

    So I'd just like to start by conceding that scripted dialogue is not my strong point.

    I tried to make a few films back in my student days and they were, let's face it, pretty hammy... pretty bad! Still, I tried and resultantly I learned something about myself... Mainly that I'm better at drawing stuff than writing compelling stories, witty dialogue and believeable characters.

    With that in mind I've been writing, re-writing, then RE-re-writing dialogue for my game, PowerUp. I know I'm not particularly good at it... but I've had some practice now, and thanks to that I'm not particularly terrible at it either.

    Sure it's all an obvious mishmash of my sci-fi influences, piled up high with every "invasion" cliche in the book... but when PowerUp's HATI (your Holographic Artificial Tactical Intelligence) piped up that there was a "Dark Intelligence" at the heart of our reptillian enemy, it began to dawn on me that I might have a great subject for my next blog.

    Let's find out if I was right, eh. Because in today's ramble, I'm going to tell you about...

    PowerUp - The Evolution of Enemies

    Yep. That's right. I've decided to let you in on snippets of the process I encountered when creating enemies for PowerUp!

    I don't mean that I'm going to bore and alienate you with reams of badly-written code (this is my first attempt at a C# game, after all), instead I thought that as I pretty much coded PowerUp chronologically, I'd go through a load of the baddies from beginning to end in the hopes that any fellow aspiring coders, designers, artists, sound technicians and musicians who follow my shenanagans might feel that little bit less intimidated by the seemingly vast complexities of this aspect of making their game.

    I can only really speak for my own experience, but once I'd mastered the control mechanics, scrolling backgrounds and pop-up dialogue of my game, I personally became sick to my stomach at the idea of populating PowerUp with challenging and engaging baddies.

    I found that coming up with enough variety in visual design and attack style just knocks on to too many of the game's other facets, which in itself can make it all seem pretty daunting... not to mention the technicallities of actually making it happen! All that said, once I stopped with the panic, broke the workload down and approached it in a calm, realistic manner, I began to see some light at the end of the tunnel.

    I also began to see the process for the profoundly fun, rewarding and prolifically creative outpouring that game development is supposed to be, and that the creation of my baddies actually really was.

    ...That sort of thing is why we wanted to make games in the first place, right?

    A Place To Begin

    So there I was. My player ship, now universally known as "Weapon-F" worked! She ducked and wheeled around the screen with grace and poise. Her arsenal was formiddable, her finer functionallity all but complete. The environment soared by in thick paralax, jumping to the next silent, abandoned game segment on cue, tracking my progress through the game as I closed in on the empty screenspace that was my first level boss. It was beautiful. It was promising... it was boring!

    It was time to bite that bullet and start thinking about baddies!

    I generally go quite a while between my blogs, I put most of my time and efforts into the game, so admittedly I forget what I've written in previous blog installations. still, I'm pretty sure that regular followers will remember me mentioning that while PowerUp was inspired by certain classic games I played growing up, my decision to actually try to make PowerUp was mostly inspired by the advice of a good friend and a good tutorial that piqued my interest in creating my own XNA shmup. Alongside basic controls, the tutorial introduced me to the concept of thowing instances of an enemy at the player... Just a simple animating sprite that moved from right to left while the player dodged it, shot it, or was killed by it.

    So far I was coping nicely...

    Enemy: Space Debris - Non-Sentient Moving Targets

    After some head scratching and a spot of umm-ing and aaah-ing, I realised that with a little modification, I could turn this simple tutorial object into something just slightly more complex. I decided I'd start with a bit of space debris, rolling through space from screen right to screen left, but essentially mimicking what I'd learned.

    Every second or so, my space debris would spawn another instance of itself, just off the right of the screen. It would then run a rotation animation (yes, animation. there was no mention of rotation in my lessons so I simply didn't have the nerve to even attempt it in code), while updating itself to move a few pixels to its left every frame of the game..... I say a few pixels, but I'd actually learned how to do this in vectors rather than real pixels. Vectors basically allow you to apply a decimal point speed, like say, "1.2" to the baddie rather than telling it how many pixels to move by. believe me, it makes things much easier later on.

    Now it was just a question of what happens next... I decided that it I wanted to avoid being overwhelmed, I'd better deal with this enemy one action at a time. I started by looking at what happens when it goes off the left of the screen. The last thing you want is your game to crawl to a crashing halt half way through because over the course of a half-hour play of it, every single baddie is still running its code somewhere off the screen! Obviously, once my debris had reached and exited screen left, it was done with. I removed it without ceremony. Blink. Gone!

    Next, it was a question of what happens when the debris collides with the player... Simple! I wanted the player to run its death sequence, and I wanted the enemy to remove itself. I tend to add whatever is needed as and when its needed so it actually wasn't until this point that I wrote the beginnings of the player's death sequence. It began as a take on the arc-up,-then-drop-off-the-screen death of many shmups of the retro era, but then I realised I could maintain a little control over the ship and even do something of a "parthian shot" death! Nice!!... hmm, but I digress and that's probably a story for another blog post. But what was evident was that there would need to be an explosion when player and enemy hit one another.

    Adding an explosion was much the same as adding a baddie, except where the baddie was being added on a timer, the explosion was being added on a prompt. Later I went back and garnished my explosions with sparks, chunks and other bits of loveliness, but to start with, I had my explosion. And that was just fine by me.

    I gave the debris the same outcome on collision with all of the player's projectile types... quite a time sink which I'm sure there's a better way of doing on my later projects, but in the meantime, a lot of player collision was copied and adapted for all of the player's projectiles, and now the player was able to shoot the debris right out of the sky.

    And there it was! A fully functional piece of space debris with all of it's possible outcomes covered.

    1. Hit player - remove with a bang and kill player.
    2. Hit player's projectiles - remove with a bang and kill player projectile.
    3. Bypass both player and bullets and get to the other side fo the screen - remove.

    Upon playing the game through I came to realise that things were looking a touch repetitive. At the very least, I needed to add a few different variants of debris to this section of the game. Not only that, but I wanted to give each piece of debris some slightly different qualities of their own. I looked at what variables I had to play with and came to the conclusion that I could change the size, strength and speed of the debris pieces... so I did just that.

    I made a few copies of my debris code and after creating a few graphical variants in Photoshop, making a few changes to the size of each debris' collision detection, and fiddling around with that decimal-point speed variable, I was able to forge several more bits of debris. The bigger they got, the slower they moved and the more shots they took to destroy.


    Space Debris - as simple as baddies come.

    Finally, I topped the attack-wave off with a nice big, tough monster chunk of debris... something of a little sub-boss.

    A few of my actual design ideas were beginning to bear fruit, mainly the need for focussed powering-up of the player's weapons... but I'd also seen how once created, a solid bit of code could easily be re-used and adapted for the next enemy.

    And that's exactly what I intended to do...

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