Tag Archives: Game Design

Jetboard Joust Devlog #94 – The Armed and the Dangerous

So far this year I’ve been focussing on weapons and the weapon unlock/upgrade mechanic in preparation for doing the wider gameplay and difficulty balancing. I’ve broken this down into three key areas…

1. Ammo Drops
It became clear whilst testing the bosses that the way I was calculating ammo drops was flawed and I needed a better method. The method I eventually came up with is simpler than its predecessor, works far more effectively and should ‘scale’ automatically as weapons are upgraded and the player faces enemies that soak up more ammo. For each weapon I now work out the maximum amount of damage that can be done to any enemy from a clip’s worth of ammo (the amount contained in a single ammo drop). I then scale this amount based on the accuracy of the weapon in question (weapons that have a lower accuracy scale down more as one must assume that not every shot will hit its target). Once the player has dealt out damage to any combination of enemies that exceeds the resultant ammo refresh rate a new ammo drop is awarded. It’s important to record the damage dealt as the amount of damage that would be dealt if the enemy had infinite health, otherwise enemies that are destroyed by the attack score too little and this can really skew the system.

To test this I set up a ‘sponge’ enemy that does nothing but takes loads of damage and tried out all the different weapons on it in turn, tweaking the accuracy scaling and checking the method I was using to calculate the max damage per clip was correct on each one. This was easy for weapons that simply fire bullet-style projectiles but more complex for weapons like the flamethrower. For ‘area of effect’ style weapons like the grenade launcher, RPG and sonic boom I can only really approximate an idea of maximum damage.

Whilst in the process of the above I got pretty distracted re-working the shotgun blast effect as it still didn’t seem to give an accurate indication of the blast’s area of effect. This is the third time I have re-worked this(!)

2. Weapon Switching
To date the player has only been allowed to carry one weapon at a time. If the currently armed weapon runs out of ammo they were automatically switched to the default weapon (pistol) which has infinite ammo. If they wanted to arm a more powerful weapon again (pretty much guaranteed) they would have to pick one up from a weapon crate AND find an ammo drop to recharge it should it have run out.

I decided this mechanic was no fun and therefore, according to the Scott Rogers principle, had to go. Now I am allowing the player to carry two weapons at once – the default weapon with infinite ammo and a (generally) more powerful secondary weapon. If the secondary weapon runs out of ammo the player is switched automatically to the pistol as before but this time all they need to do to recharge it is collect an ammo drop. The new mechanic seems to feel much more natural and fun to me, though I’m a little worried it might give the player the opportunity to over-exploit powerful weapons but we shall see…

As an adjunct to the above I also implemented a key to switch weapons so that the player can switch to the pistol if they want to save ammo on powerful but understocked weapons such as the RPG.

3. Weapon Unlocks
Previously, in order to unlock a weapon, the player had to catch the jetboard of an enemy that was armed with it. This worked OK, but it was a bit easy and I didn’t really think it made a big enough deal of the weapon unlock process.

I’ve decided instead to have weapon unlocks as a type of treasure. Rather than being guarded by a boss, the treasure chambers that contains these weapon unlocks will be guarded by a fleet of enemies armed with the weapon in question. This enables me to make more of the treasure chamber mechanic, adds another layer to the gameplay, and also allows me to use the big ‘weapon upgrade’ icons (which I was rather pleased with) in-game as pickups.

It didn’t take me long to design these ‘guardian’ enemies but I spent a fair bit of time on implementing some special AI for them. Firstly I enabled them to swoop down and steal the player’s health pickups to heal themselves (I may allow other enemies to do this once the reach a certain level), and secondly I implemented a special ‘wrap attack’ whereby if a bunch of them have been chasing the player in the same direction for some time a few will take advantage of the world wrapping by peeling off and heading in the opposite direction to meet the player head on!

The video demonstrates unlocking the shotgun by defeating a small fleet of enemy guardians. They’re pretty tough opponents – as you can see I had to rely pretty heavily on the jetboard attack here and was pretty lucky managing to take out three of them in one go!

Dev Time: 241.5 days
Total Dev Time: approx 4.5 days

previous

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Using a ‘Bullet Sponge’ to Test Ammo Drops

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Enemy AI Now Enables Them To Steal the Player’s health Pickups

Unlocking The Shotgun – Note The Guardian’s ‘Wrap Attack’ Technique

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Jetboard Joust Devlog #55 – The Bubblewrap Effect

Everyone loves popping bubblewrap, yet no-one really knows why. For some reason the combination of the sound and tactile response makes it incredibly satisfying despite being utterly pointless. I had a friend who use to refer to this type of action as being ‘urgey’ – once you’ve done it you have the urge to do it again, and again, and again…

I’ve always thought we should aspire to this ‘bubblewrap effect’ when designing games. Most games, even the supposed AAA ones, comprise a fairly limited set of repetitive actions. If you can make those actions an enjoyable experience in and of themselves, regardless of gameplay, then you are onto a winner because no matter how good the player is at playing your game they will be having fun and come back for more.

Recently I’ve seen this loosely referred to as ‘juice’ or ‘game feel’ but these terms are rather vague and are often used to refer to all sorts of things. I’m talking about something pretty specific here – make all your repetitive actions as ‘urgey’ as popping bubblewrap. Usually this is a combination of both visuals and audio.

Now I’d already spent a lot of time on this stuff in Jetboard Joust but, whilst surfing GDC talks on YouTube, I came across this excellent talk by Jan Willem Nijman of Vlambeer on adding these types of elements to your game. I’d already implemented many of the techniques he talks about (camera shake, gun recoil, enemy and player knockback etc) but he made me rethink some aspects and put a bit more effort in to areas that were somewhat lacking.

So – here’s what I’ve been working on as the result of @jwaaaap‘s talk.

1. Bigger Bullets
To be honest a) this would never have occurred to me and b)I never would have thought it would work if it did. I was using little pixel squares for bullets as 1) they seemed appropriate for the size of gun and 2) this worked in Defender so why fix what ain’t broke? But I thought – ‘what the hell?’ and gave it a go. I started increasing the size of the bullets a little and was amazed how much better this felt, so I increased them what I would have thought was a ridiculous amount and it felt even better! It makes no visual sense whatsoever but the pistol (and particularly) the gatling gun are so much more satisfying to shoot now. I haven’t tried playing with the accuracy yet but should really do that too…

2. Camera Knockback
I already have some pretty hefty recoil on weapons but @jwaaaap suggests also recoiling the camera a certain amount when a weapon is fired. This didn’t make a massive difference in Jetboard Joust, probably because the camera is generally moving pretty fast anyway, but it is noticeable under some circumstances so I left it in.

3. Explosion Delay
Adding a very slight delay when an enemy is destroyed adds to the ‘jolt’ effect and makes destroying enemies much more satisfying. It’s subtle but it works. I’m using a delay of 32ms. I had to be careful here to not implement the delay until the next frame (ensuring the first frame of the explosion is drawn before the delay occurs) and also to clamp the delay time so that destroying a bunch of enemies at the same time didn’t result in a massive delay. I also improved the first ‘flash’ frame of the explosion by adding a ‘threshold invert’ to my collision shader and making the circles that briefly appear larger, brighter and less pixelated. Enemies really look like they’re getting nuked now!

4. Permanence
I had been wanting to do something to make battles seem more ‘permanent’ for some time and @jwaaaap‘s talk was the kick up the arse I needed. I talk about adding smoke in my previous post but that’s still not really permanent so I also added bones that fall from enemies when they’re destroyed and collect on the ground as a permanent record of the carnage that’s ocurred there.

Adding the bones was easy, the trouble started when I decided that they were too static and should react if the player hit the ground near them or crashed into a building that they were resting on. I didn’t want to run collision checking on every bone (there can be tons of them by the end of a level) so worked out a system whereby the world is divided into a series of overlapping ‘bone zones’. When a bone is static it is added to a zone and an entire zone can easily be discarded from the collision detection process in one go. I’ve used this approach before and it works well but I got myself into a bit of a flap with it here, plus it took a long time tweaking the various parameters so that the bones seemed to get disturbed by the correct amount. It still looks a little odd sometimes but its much better than having them totally static.

I’d really like to add some permanent damage to the buildings but I haven’t yet figured out a way to do this that would be a) be cpu/memory efficient and b) not involve creating a load more pixel art. I will continue to give this some thought – it could be that I’m underestimating the memory available on modern devices as a spent so long developing for J2ME feature phones!

So I hope that was all worth it and makes my game feel a little more like popping bubblewrap. I’d like to say these were the last gameplay tweaks before I release the alpha but watching my son play it has led me to implement just a couple more things…

Dev Time: 2 days
Total Dev Time: approx 99.5 days

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My… What Big Bullets You Have!

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These Bullets Are Ridiculous – But Somehow They Work!

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Explosion Delay (Exaggerated), Smoke, And Improved ‘Flash Frame’

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A Battle Amidst The Bones Of Fallen Enemies

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Bone Bashing – A Stupid Detail That Caused Me Much Grief!