Blood & Bullet will soon change name to:

You assume the role of team leader in the tactical response team of a major city police force. Your work is to plan and carry out tactical entry in barricade and hostage situations with the least possible loss of life the desired outcome.

Blood & Bullet is a side-scroller that strives to provide a realistic model for projectile interactions and injuries. Once someone is hurt the player will be working against the clock to save them. Gear and tactics must be chosen carefully to minimize damage and resistance.

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Character physiology in Blood & Bullet

I want a couple of key features in Blood & Bullet to be realistic. One of those are how characters are injured and what the effects of the injuries are. I am by no means an expert but I use the knowledge I have and what I'm able to find. Since the characters in my game are 2-dimensional I have to play some tricks to simulate the third and missing dimension.

The characters' bodies are composed of limbs, and to each limb I can attach what I call vital properties. When a limb is hit by a projectile I randomize which of the vital properties are hit based on probabilities for each of the properties. For instance hitting the spine inside the torso has a much lower probability than hitting the lungs, since the lungs cover a larger volume of the torso than the spine does.

Some of the vitals I can add to limbs are as follows.

Locomotive bones
These are bones that are necessary for the character to move. When these are damaged the character will start to limp and if the impact is powerful enough it will knock the character off its feet. This is used in all the limbs from the feet up to the pelvis.

Major blood vessels
If these are hit the limb will bleed at its maximum rate. Depending on which limb it is it may cause the character to bleed out and loose consciousness very quickly.

Lungs
When the lungs are hit their capacity to store oxygen is reduced.

Heart
When the heart is hit it will function less efficiently and skip beats or stop completely. The amount of oxygen transferred to the blood is reduced.

Spine
When the spine is hit I want to turn off motor control to the limbs below the hit region but I can't do that yet. Now the character simply falls to the ground.

Brain
When the brain is even slightly damaged the character loses consciousness. Further it is divided into a couple of parts making it possible for the character to lose:

  • Circulation control - the heart stops
  • Respiration (breathing) control - respiration stops
  • Motor control - muscles in limbs cramp or spasm

What it takes to stay alive

For a character to remain alive in Blood & Bullet its brain must be intact and supplied with oxygen. That is the only criteria. If the brain is too damaged the character dies. The brain receives damage both from trauma (projectile hits) and over time by lack of oxygen. The brain can be without oxygen for 30 seconds before it dies. That value is game-ified of course and it will probably be different depending on the level of difficulty selected.

For the brain to be supplied with sufficient oxygen both the character's respiration and circulation must function properly, meaning it needs to breath and the heart needs to beat. As you saw above, both of these can be impaired by trauma from being shot, or disabled completely if the brain is hit. The character is unable to remain conscious when the oxygen level becomes low and this happens long before brain death, so a character lying on the ground in Blood & Bullet is usually just unconscious and not dead.

Work intensity

On the characters I have a value that represents how hard they are working themselves physically. It becomes high when they are running and it's low when they are standing still, but everything they do takes work. Even breathing and pumping the heart takes some work.

This is the basis of the physiology in B&B:

  1. A character breathes and pumps blood to provide itself with oxygen.
  2. The level of work a character does directly affects how much oxygen is taken from its blood.
  3. When the amount of oxygen in a character's blood becomes low, its heart compensates by pumping faster. This removes oxygen from its lungs faster but provides more oxygen.
  4. When the amount of oxygen produced by a character's breathing becomes insufficient the character compensates by breathing faster.

This all fits together rather neatly. While tweaking it I was pleasantly surprised when I managed to strain the player character so hard by running that he lost consciousness!

WalkingPulse during walk

Above: Pulse, blood pressure, respiration and work intensity during a walk.


RunningPulse during run

The same values some time into a sprint. Note that also the blood pressure is higher during work because it must circulate faster. Diastolic pressure is the lowest pressure during the beat cycle that occurs while the heart muscle is relaxed.


How it affects gameplay

Now that you understand that the characters in Blood & Bullet have "real" pulses you can see that a character that has been working hard will bleed out faster than a character that was resting if they were injured, because the heart pumps the blood out of the wound faster.

You can see that stabilizing a downed suspect to make him bleed slower may buy you time to finish the mission before he dies. (Proper healthcare cannot be provided before you have secured the building.)

You can also see that it's equally important that you make sure unconscious characters don't suffocate from having their breathing obstructed.

You will have the option to equip your team members with medical kits that can stop or slow down bleeding. It will be up to you to decide when to use them. Some missions may be so time critical that you simply don't have the time to stop before you have cleared the whole building.

It is my hope that this adds to the gameplay and that it puts the use of force into some perspective. At least for the campaign missions. The sandbox mode is quite different in how it is played but the same character physiology is in place there as well.

Thanks for reading!

Behavior of occupants in Blood & Bullet

Behavior of occupants in Blood & Bullet

News 6 comments

I go through a bit of the current artificial intelligence in Blood & Bullet, implemented with behavior trees. Skip to the end for lots of animations.

Realistic ballistics in Blood & Bullet

Realistic ballistics in Blood & Bullet

News 7 comments

I go through parts of the fairly sophisticated ballistics model in Blood & Bullet.

What happens next?

What happens next?

News 3 comments

It's been a long time coming. I'm now looking into a new way of developing Blood & Bullet. All in order to make more efficient use of my time.

Signs of progress

Signs of progress

News 5 comments

I've been working in the quiet lately but it's time I posted a new update.

Real Gun Sounds

Real Gun Sounds

Other 4 comments

INSTRUCTIONS: GO TO DATA > AUDIO AND REPLACE SOUNDS

Release 1

Release 1

Enhanced Bodies Demo 0 comments

First release / possible demo / full release of the addon. Tip: Backup your hostage files before installing. To do that, go to "bloodandbullet/data/graphics/bodies...

Demo 3

Demo 3

Demo 30 comments

The third Blood and Bullet demo adds more game play mechanics. Use concussion grenades to overwhelm the suspects. Restrain them, secure their weapons...

Demo 2

Demo 2

Demo 2 comments

This demo is more of a taste of game play than the previous one, but still with some obvious parts missing. There are more weapons, a bit of AI, rooms...

Sandbox/tech demo

Sandbox/tech demo

Demo 4 comments

This is not a game-play demo. I just want to point that out. It's a sandbox/tech demo of the features so far. It's scaled down a bit to keep it simple...

Comments  (0 - 10 of 289)
BrodyTheWonder
BrodyTheWonder

I first started playing B&B when the third demo came out and the progress you've made since then is nothing short of spectacular! The gameplay reminds me of the old SWAT fps games from the early 2000's except that this is way more realistic and interactive. Thank you for taking time out of your day to create such a masterpiece, isbeorn. Your work means a lot to the folks 'round IndieDB (among other websites)!

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isbeorn Creator
isbeorn

Thank you for following all this time and for writing this, comments like this one mean a lot to me. And it makes me very happy that you think B&B is more realistic since that is one of my main goals. It's been a long time since demo 3 but the next demo will be ready very soon!

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Cantalouper
Cantalouper

News on a release? :)

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isbeorn Creator
isbeorn

All my predictions seem to fail, but I've started postponing things until after the demo release to not delay further. Well only things that aren't completely necessary for the demo. I have a road map where the demo is the first step. That's my motivation for releasing soon, that I have to before I can start working on the other other things; the campaign and other interesting stuff. :)

It should be a matter of weeks. But I work as I go and there's no detailed plan so at the same time I don't really know.

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DocMale23
DocMale23

CRISIS RESPONSE ? WOT ?????

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isbeorn Creator
isbeorn

Yes! As I vision it, that better describes what the finished game will be. What I've shown so far is only one half of the gameplay I have in mind. :)

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arizxna_kvsh
arizxna_kvsh

I like it.
Are you going to base some future content off real life terrorism occurances?
ISIS and all that kinda crap?

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isbeorn Creator
isbeorn

No, I don't think I'll include any terrorism. I do want some bigger and more complex missions for the campaign but I can probably come up with some other background for them.

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UltimateHeron
UltimateHeron

And yeah, can you pleeeeaaase release any of the latest builds on old engine somehow? I'd (and not only me i think) really like to see them.

It would be really interesting to check it (or them) out not only to see how your ideas progressed but to see the engine itself. I mean, dude, you have built it from scratch!

I would sincerely appreciate if you do.

I dream about it literally every few days.

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DocMale23
DocMale23

Nice idea ! Sniper mode...:P
PLZ PLZ PLZ PLZ PLZ PLZ PLZZZZZZZZ. Realise it :(

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UltimateHeron
UltimateHeron

Exactly!

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isbeorn Creator
isbeorn

I actually tried it yesterday, I found a state in the version history where the sniper mode was working. But I had problems compiling it in release mode. So I didn't quite make it all the way. Maybe I can finish it next time I have some spare time.

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UltimateHeron
UltimateHeron

Cool!
That's actually some great news! At least we've got yourselves some hope now.

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DocMale23
DocMale23

rlly ? That's sad :d

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UltimateHeron
UltimateHeron

Maybe as a bonus for the unity realese? Idk just by any possible reason.

Pleeease.

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isbeorn Creator
isbeorn

I'm sorry I just can't do that. It would take too much work. But you will get to enjoy the Unity version soon. It builds on everything I learned from making the previous versions and it's much better in every way!

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UltimateHeron
UltimateHeron

ikr

But why? I understand that if its too much work it won't be worth it... But I also thought that you had a working build and just didn't want to give it to us cause it wasn't finished.
I mean, you didn't completely delete it, right? So maybe there's a slim chance that it will happen?
Again, I understand that if you have to restore it somehow in order to get it working or smth. But if its not the case why not?

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isbeorn Creator
isbeorn

Yeah that's the thing it's not in a working state. There might be some state in the version history that is restorable with some work, but honestly to me it's not worth it. The work of finding that version state, and then the work of restoring it is time I want to spend on moving forward with the current game. Thanks for understanding!

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Blood & Bullet
Platforms
Windows
Creator
isbeorn
Engine
Unity
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Latest tweets from @bloodandbullet

Today I'm adding convenience functions to the team equipment menus for quickly copying equipment between the operators.

Jun 23 2016

Bug fixes today! And more game-play streamlining, in form of showing mission objectives at the start and other small things.

Jun 22 2016

I'm improving weapon rendering in the equipment user interface. Before it hasn't re-centered weapons when components are attached.

Jun 16 2016

I'm nearly done with a big overhaul of how the weapon components work. They've been a bit iffy for some time.

Jun 13 2016

I just added a notice to the IndieDB page that B&B will soon change name to Crisis Intervention. It's a better fit for where it's heading.

Jun 10 2016

I just made real-time shadows optional, it will be good to turn off on low-end machines. Now I'll continue on the equipment UI.

Jun 8 2016

More fixes for the AI and menu system today.

Jun 7 2016

I'm working on a few bugs with the AI's weapon handling today. Teammates would not release their trigger when you stepped in the way. Bad.

Jun 6 2016

I will finish up the tutorial today, then I will address a few remaining issues in the equipment selection screen. T.co

Jun 3 2016

Today I'm starting the making of a tutorial level. I've been looking forward to this!

Jun 1 2016

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