Realistic damage models

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This is part two of the Weapons series. Read Part One: Realistic weapon behaviors.

Warning: This article will be discussing damage to the characters and contain detailed  descriptions of wounds and their effects.

If you played any recent games that involve combat, you’d have noticed that they all use “hit points” to model damage. They may sometimes be called “health,” “vitality,” or “physical condition,” but the underlying logic is the same: You get a number representing how close a character is to death. As a character gets attacked, any damage they sustain gets subtracted from the available hit points, and once you reach zero, you die. Simple, and elegant, right?

Well, simple it may be, but this model is also completely unrealistic. It forces many weapons to be less useful than they should be; it takes away from the challenge of the game; and finally, it turns combat into a war of attrition where the player and enemy take turns shooting each other until everyone on one side is dead. All of these things are undesirable in a realistic game.

Life is full of complex balances and trade-offs, and a realistic game will seek to replicate that as closely as possible. So what is this going to look like when it comes to damage?

Realism

In most games, getting shot in the leg is a good thing. You take minimal damage and otherwise proceed unhindered. That would not work quite like that in real life.

No human has a hit point rating. When people get hurt in combat, they can’t just go on as if nothing happened until all their life points are gone. In a realistic setting, even if all you got was a flesh wound, you’d start to limp at a minimum, but if the bullet hit a bone, you may not be able to walk or even stand anymore.

To model this correctly in the game, our weapons won’t have any damage ratings. Instead they’ll be rated for the type of projectile they fire, and the energy with which the projectile leaves the barrel. From this we can calculate how much energy the projectile loses from air resistance on its way to the target.

If the target has armor, it will slow or stop the projectile. If the projectile is stopped, there may be no damage at all or some blunt damage depending on the armor type and energy involved. If the projectile did penetrate the armor, things will get bad for the target.

In the previous post we talked about accuracy and how hits are determined. So at this point we know: 

  1. where the target has been hit, 
  2. with what kind of projectile, 
  3. and with how much energy (how fast) the projectile hit.

From all this data we can generate a realistic wound by looking at the body part that’s been hit. The system looks at what organs or structures there are, and calculates how much damage has been caused based on the velocity of the projectile and its shape. It’s possible that the bullet will pass through-and-through, as is common with small-caliber armor piercing rounds. In that case it may hit additional objects.

So now we have calculated one or more wounds, e.g. a broken leg, or a damaged eye, a direct hit to the heart, or an arm flesh wound. Just reading this list, you can probably imagine how each of these would limit a character. Some injuries may have more complex outcomes, when they don’t drop the target outright, but limit the character's ability over time.

Depending on the severity of the wound, there will be periodic heal/die checks. Some wounds will be life-threatening, in which case we’ll calculate a survival chance, and check frequency rate. Passing the heal check doesn’t mean the wound is healed, only that it’s no longer life threatening and the character will survive. Medical aid will change the odds for each wound, improving the chance of survival. Medical aid can also reduce the frequency of survival checks, so in some cases it buys the time to get the character to a proper hospital.

Now that may sound scary, but it should make for a more nuanced and interesting gameplay. You’ll have more options for selecting the right kind of weapons for all members of your party, depending on both their talents and the objective.

Take for example the small concealed pistol. There’s a reason they exist in real life, but in your typical game they are pretty much useless. With this system, they can be useful once more, provided you can avoid the armored parts of your target and hit a sensitive spot.

Same goes for armor and combat tactics. Do you bring heavy armor to the fight hoping to stop any rounds headed your way, or do you rather focus on not getting hit at all? Heavy armor will make you slower and more conspicuous, while light armor or none at all may increase your agility, but makes the consequences of getting shot much more serious.

As a result of balancing the objectives with risks, as the game goes on, every player will end up building a very unique party, best suited to their playing style.

That’s it for today. Our next post will deal with encumbrance and movement.