Apr 4, 2012

Abolishing Hit Points

This is a theoretical exercise that I've never tested out, though I think True20 does something similar.

I was reading this paper on handgun wounding effectiveness factors and was struck by the parsimony of the descriptions of injury. Either someone is incapacitated or they are not. Adrenaline and endorphins make pain responses much less likely, to the point where falling down and clutching the wound when getting shot in combat is a learnt behaviour according to the author. Incapacitation results either from blood loss (specifically loss of blood pressure and the capability to efficiently transfer oxygen to muscular tissues) or from damage to the central nervous system.

One of the interesting things the author discusses is how temporary cavities do not generally contribute to incapacitation. That is, when a bullet hits you, the force temporarily pushes your flesh apart, but as it penetrates or stops moving, the flesh flaps back closed behind it, with only a smaller, more permanent cavity being important. Handgun bullets and other projectiles tend to leave only small permanent cavities, which must penetrate into the central nervous system, key blood vessels or other organs where a small loss of mass is sufficient to incapacitate the person. The end result of this is many people, when injured but not incapacitated by a weapon, just keep on doing whatever they're doing (trying to kill you or run away from you, mainly).

I've been considering whether this kind of knowledge could be usefully transferred into damage systems in games in such a way that it is not simply a binary system with "alive and fully functional" and "incapacitated" as the two categories. Specifically, I want a way to track when someone is maimed but not incapacitated (for fantasy games where swords can cleave off a hand or arrows can put out an eye) and when someone is not currently incapacitated, but is bleeding out and will be eventually. I think it might also be useful to cover when someone is specifically dead, and not just incapacitated. I'm not sure a track is the most effective way to handle this.

One possibility I've been considering is making damage rolls a sort of reverse saving throw with gradations, where the attacker's roll must exceed certain values in order to inflict each one of the four injury possibilities. I favour these values ascending with level, rather than being based on Constitution or another ability score, so that there is something like, but not quite the same as, ascending HP.

For example, a 1st level fighter might have injury scores of 8/12/14/16, where the first covers bleeding, the second maiming, the third incapacitation and the fourth instant death. An attacker rolls a d20 to attack and gets a 13. The fighter is bleeding and maimed, but not incapacitated or dead. If the attacker rolls a 14, the fighter is bleeding, maimed, incapacitated and dead.

As a possible variation to consider, I might stagger the results so that it goes bleeding, incapacitated, maimed, dead, which would order them in terms of the permanency of the result rather than the severity of the effect on combat capability.

The effects of each status:

Bleeding: Attacking a bleeding opponent adds +2 to your attack roll (thus making further damage more severe). People who are bleeding out may make a saving throw at the end of combat to stop bleeding.

Incapacitated: The person is unable to perform strenuous activity and is either unconscious, in shock or writhing in pain. Attackers get +4

Maimed: The person has a piece of themselves permanently destroyed or detached. Attackers get a +2 to all attack rolls.

1 Right Leg
2 Left Leg
3 Right Arm
4 Left Arm
5 Torso injury (spinal, respiratory system, circulatory system)
6 Facial injury (eye, ear)

Death: The character must immediately make a saving throw or die.

This is all very tentative, so I'd appreciate feedback and / or offers to playtest it.


  1. I feel like this should somehow interface with the phenomenon where someone is injured, and is certainly going to die of that wound (barring magic or something) but probably won't die for a while.

    1. Yeah, I'm taking recommendations for that very thing if you have any.

  2. I like BIMD rather than BMID. Otherwise low-level PCs will constantly be getting limbs lopped off.

    I'd suggest a save for any maimed person, fail = death in 1d6 days. A trained healer on hand will give +2 to the roll (that is, do the "dead in d6 days" roll after combat). If you can get magical healing, you don't die but you need some high level magic to recover from your maiming.

    If you fail your save after battle to stop Bleeding, you move into Incapacitated until you get magical healing or 1d6 days rest.

    I like this system. I'd run this as a saving throw, and the attacker is assumed to have hit if the save ends up being too low. Your 1st level Fighter above would have a save scheme of 5/7/9/11 for the DMIB levels. My reason for this is to give the defender the roll, which puts a player's fate in his hands. It also helps to stack modifiers onto a single save for each round rather than making multiple attacks per round.

    So for example, if I'm a F1 being attacked by an Orc, I need to roll my save at +0. If I'm attacked by a Kobold (1/2 HD) I save at +1. If it's an Ogre (4 HD) I save at -3.

    Multiple attackers use the highest HD plus half the lower ones. That means out F1 attacked by 5 Orcs at once would be fighting a 1 HD Orc plus (4 x 1/2 = 2) 2 HD of other Orcs, so his save is at -2. An Ogre and three Orcs would offer a save of (save at -3 for the 4 HD Ogre, plus an extra 1.5 for the 3 HD of Orcs) -4.5 (which I would round up to 5).

    A 10th level Fighter fighting 10 Orcs would roll at (+9 because an Orc is 9 levels below him, -4.5 for the extra 9 HD of Orcs) +5. Note that 8 Orcs can surround him so this means all 10 must be shooting him with arrows. Normally you'd never have more than 8 enemies hitting you at once. Assume this includes any rear attack bonus on behalf of the surplus Orcs. Anyway, even naked this Fighter can't possibly die, and will be maimed only on a save of 1 or 2 on the die. He has at least a couple rounds of being chewed up before they can get a kill in.

    Armor will help your save depending on the armor type. For example, metal armor doesn't help against electricity very much. Magic armor might add a special bonus against fire. I'd suggest Leather as +2, Mail as +5, Plate as +7, and Shield as +1. This is the AC value of said armor in 1E/2E D&D. A F1 in Mail and Shield would have DMIB saves of -1/1/3/5. He has a 75% chance of avoiding attacks from 1 HD monsters, which is comparable to an AC 4.

    You don't need a special effects list for each damage type, because you could rationalize being incapacitated by cold or maimed by heat etc.

    This system makes multitudes of low-HD creatures worthwhile. It's possible for 30 villagers to mob a knight and take him down ... although will they be willing to knowing half a dozen will die in the process? A swarm of Giant Rats is a nasty encounter.

    Here's an extreme example: a swarm of 16 Giant Rats (assume this DM is mean and 16 can attack one Fighter instead of 8 due to their size and climbing on him) against a F10 wearing Plate +2 and Shield +2 (total DMIB save is -7/-5/-3/-1). The first Rat is 1/2 HD and the other 15 rats are worth 7.5 HD, so our total attack is 8 HD. That's 2 HD below the Fighter, giving him +2 to his save. It's impossible for him to take damage from the rats.

    But what if he was naked? His DMIB is just the standard 5/7/9/11. With +2 because of his level relative to the rat swarm total, he could still die on a roll of 3 or lower on his save.

  3. There is a problem with this system, like any which combine the attack and damage roll. You can't have a monster with a low chance to hit but high damage, or a monster with high chance to hit but low damage. I think the broad range of D&D monster examples has few outliers like these so their absence from the system could be ignored.

    My multi-monster rule assumes a monster will attack just one target. If it has an area-effect attack (like Fireball) apply the save modifier to everyone in the area that round. If you really must have monsters with multiple attacks that strike different targets, apply the creature's HD to all targets. That's equivalent to how it works in D&D.

    You could refit this system for shades of grey save-or-die effects. For example, a poison could have varying effects at each DMIB level. Saving poorly gives you a different effect from just barely failing. Similarly, maybe Petrification causes no effect on Bleed or Incap but on Maim one of your limbs is stoned and on Death you're totally petrified.

    The nicest thing about this alt-damage system is that you can use all the OSR / 1E / 2E materials for it without alteration. A Wand of Polymorph has a caster level. A Stone Giant has his AC (which you can translate into a DMIB save by modifying the save down by 1 point per point of ascending or descending AC). It should make fights faster and waste less time with the Cleric rolling for Cure spells after the fight. Narration of the fight becomes a whole-round affair rather than individual attacks - more coherent. And it sounds like it would work wonderfully for declared-initiative combat.

  4. This reminds me a little of Savage Worlds. I don't have any suggestions on how to use or improve it, but I know that I like the way SW handles damage and incapacitation so if this system of yours is similar -- and on a superficial level it seems to be -- I can see it working well.

  5. I've run the True20 saves and an adaption to GUMSHOE which worked pretty well too. I like how it feels dramatically in play; a little bit more like a Warhammer armour save. I'll finish the writeup for the GUMSHOE version sometime.