What are hit points? The most obvious answer is that hit points are a numeric index between healthy and imminent death, but there are other interpretations of the significance of this ubiquitous character statistic, and some of them lead the GM down interesting paths. This article will examine the first of these options, while parts 2 and three will examine a second and a third, even more far-reaching alternative, respectively.

Each of these alternatives has consequences for the flavor of the game that is being run, and requires house rules to interpret the philosophical metagame definition into concrete game mechanics correctly.

The Healthy and the Helpless

Another possible answer which I have seen in house rules from time to time is that hit points are a numeric index of the gap between healthy and helpless. This relates the damage that is inflicted apon a character to the impact that this damage has on his abilities, and his capacity to overcome that impact.

Before going too far with this, I have to admit that I have never run a game using this particular wounding model. Everything that is written below is unplaytested and derived strictly from RPG theory, and being written straight off the cuff.

We’ve all experienced injuries in our time – abrasions, falls, nicks. Some have had more serious injuries like broken bones or surgical wounds. And a few unfortunates have even more serious injuries in their pasts. So we can all relate to the principle that being injured slows our movements, impairs our physical capacities for action, and saps our will to act. These are responses to the pain of the injury, which is the body’s reaction to that injury; if we heed these warning signals, we heal, or at least have the chance to do so, and if we don’t then healing is slowed, may not progress properly (bones fusing out of alignment and so on), or may not occur at all (cuts reopening, etc).

We have all also seen people, especially in desperate circumstances, ignore wounds that might have incapacitated them at other times, in order to meet the needs of survival (be those their own or those of someone else).

Under this paradigm, the increase in hit points a character receives as a result of a level increase can be described as an increase in the capacity to remain functional despite injuries that may have been received, and the condition of zero hit points remaining – helplessness – is tantamount to death, should any enemy remain in better condition.

Implementation

To have the game mechanics reflect this metagame definition, two things are required: first, an index of impairment, relating the degree of injury to the degree of impairment suffered; and secondly, a table of consequences which define the consequences on other game mechanics of the impairment that a character may suffer.

Index of impairment

Interpreting the increase in hit points as a character acquires levels as an increase in capacity to absorb injury before reaching a given point of impairment gives us the scale apon which an index of impairment must be measured – the percentage of hit points lost.

Further, since characters have four limbs, plus a head (even a character with both arms and both legs broken or ruined can bite the enemy), and there would need to be a base level of no impairment, it is easy to construct such an index as a percentage of hit points lost.

While many such tables are possible, I’m going to present three that will represent the field of possibilities.

Impairment Index 1: Simple Linear

The graphic to the right illustrates a simple linear impairment index. Start by considering the left-hand-side: at no hit points taken, the character suffers no impairment, and this persists until the character has lost 1/6th of those hit points. At the point where his damage taken crosses that 1/6th boundary, he goes from ‘impairment zero’ to ‘impairment A’ and suffers the impairment effects that match that condition. At 1/3 hit points lost, the character enters condition B and suffers greater impairment, and so on. How much impairment is something to be considered later, when we work on the table of consequences.

The left-hand section reflects external injuries and the relative impairment that results. ‘A’ can be considered minor impairment, B is impairment equivalent to the inability to use one limb, C is equivalent to two limbs, D to three, and E to four. When the character has no hit points remaining, he hits the bottom of the chart and is helpless to prevent the enemy doing whatever it likes to him.

The right-hand section concerns itself with internal injuries, and divides the potential impairment and consequences into three sections, labeled alpha, beta, and gamma. Alpha means that the character has no noteworthy internal injuries unless the weapon specifically inflicts them. Beta describes a condition where there is some risk of internal injury – how great a risk and how serious they are forms a third section of these variant rules – while gamma denotes a condition in which such wounds are more likely to have occurred and/or for them to be more serious.

If a tenth-level fighter with 79 hit points were to set up a list of ‘danger points’, it would look something like this:

• 0-13 HP lost: zero zone, alpha zone.
• 14-26 HP lost: A zone, alpha zone.
• 27-39 HP lost: B zone, beta zone.
• 40-52 HP lost: C zone, beta zone.
• 53-65 HP lost: D zone, gamma zone.
• 66-78 HP lost: E zone, gamma zone.
• 79 HP lost: totally helpless.
• 89 HP lost: death.

That doesn’t sound too unreasonable, does it? Compare that with a mage of 10th level, no CON bonus, giving him 25 hit points. 25-1=24; divide by 6 to get the intervals (4 hit points):

• 0-4 HP lost: zero zone, alpha zone.
• 5-8 HP lost: A zone, alpha zone.
• 9-12 HP lost: B zone, beta zone.
• 13-16 HP lost: C zone, beta zone.
• 17-20 HP lost: D zone, gamma zone.
• 21-24 HP lost: E zone, gamma zone.
• 25 HP lost: totally helpless.
• 35 HP lost: death.

That seems a bit nasty, doesn’t it? After 9 HP damage, the mage is either casting spells one-handed or leaning against something, unable to stand on one leg.

This scale of impairment and injury permits the rules to be adopted to be simple and straightforward, with minimal calculation required; though that is another area the GM can tailor to his own requirements.

Before we get into that, let’s consider a couple of alternative impairment Indexes.

Impairment Index 2: Biased Linear Progression

This is achieved by making the early zones larger and reducing the later zones accordingly. The example to the left shows just how broad a scope the GM has for tweaking the design. The GM who designed this proposal (me, obviously) has tripled the size of the zero zone, and doubled the size of the A and B zones relative to the C, D, and E zones. 3+2+2+1+1+1=10, so this gives an impairment index based on tenths of the character’s hit point total.

Until the character loses three-tenths of his total hit points, he is unimpaired and in the “zero impairment zone”. When he has lost half his total hit points, he is only slightly impaired – the equivalent of using the use of one limb. Until he has lost seven tenths, he is still in the ‘B’ zone – the equivalent of using the use of two limbs. Use of the remaining limbs then occurs fairly quickly, at 8 tenths and 9 tenths his total, respectively.

He has then gotten carried away with his own cleverness (note that I have done this deliberately to make a point!) and set the end of alpha region (no internal injuries) as occurring half-way through the A zone, so that a character can have nothing more than bruises and contusions but still have a risk of internal damage – perhaps a rib puncturing a lung, or something of that sort. He has then made the gamma region the same size as it was before, adjusted, i.e. overlapping the D and E external injury zones, and stretched the beta zone (some risk of internal injuries) to fit.

Relative to the even breakdown that was there before, this is the equivalent of making the Alpha zone 5% larger than it was, the beta zone 36% larger than it was, and the gamma region only 60% of what it was. The critical numbers are 7/20ths of hit points lost and 80% of hit points lost.

Personally, I would think this was overcomplicating things, but it’s certainly possible to arrange things this way.

How this is better than the simple linear index:
It defers impairment until the character has taken more damage, letting him fight for longer. And if the designer hadn’t gotten carried away, it would have been just as simple to implement. Consider the 25-HP mage from the previous example. 25HP-1 = 24 (because once he has taken 25 HP he is totally incapacitated), divide by 10 to get intervals of 2.4:

• 0 to 2.4×3 = 0 to 7 HP lost: zero zone, alpha zone (was 0 to 4).
• 8 to 10 HP lost: A zone, alpha zone (was 5 to 8).
• 11 to 12 HP lost: A zone, beta zone (combination didn’t exist before).
• 13 to 16 HP lost: B zone, beta zone (was 9 to 12).
• 17 to 19 HP lost: C zone, beta zone (was 13 to 16).
• 20 to 21 HP lost: D zone, gamma zone (was 17 to 20).
• 22 to 24 HP lost: E zone, gamma zone (was 21 to 24).
• 25 HP lost: totally helpless.
• 35 HP lost: death.

So the seriously-incapacitating zones don’t occur until the character is much closer to helplessness. Even with this fairly tight scale – the result of a low HP total to start with – the effects are evident.

How this is worse than the simple linear index:
It’s more complicated (it adds an extra condition step). It’s less intuitive as a result – we used to have three internal injury conditions, or zones on the table, each subdivided equally into two external injury/impairment zones. And worse still, by getting clever and putting the alpha-to-beta transition midway through a zone, it introduces a new calculation that has to be done on the fly.

Finally, if even a low-hit-point mage feels the benefits, how big will the effects be on somebody with a fairly decent HP total? Consider a character with 101 hits points (to make the math simple):

101 minus 1 = 100; 100/10 = 10. This gives:

• 0 to 30 HP lost: zero zone, alpha zone.
• 31 to 40 HP lost: A zone, alpha zone.
• 41 to 50 HP lost: A zone, beta zone.
• 51 to 70 HP lost: B zone, beta zone.
• 71 to 80 HP lost: C zone, beta zone.
• 81 to 90 HP lost: D zone, gamma zone.
• 91 to 100 HP lost: E zone, gamma zone.
• 101 HP lost: totally helpless.
• 111 HP lost: death.

ImageL:Wound Index 3

Impairment Index 3: Geometric Progression

Those who like consistent patterns may wish to take things a step further, making the range of each zone a multiple of the range of the zone that follows it. This achieves something similar to the Biased linear progression, only more so. The following table shows the breakpoints for a variety of geometric patterns (plus a ringer at the end).

Of course, these results aren’t all that useful as they stand. Utility – and the revelation of an interesting pattern or two – comes from converting the above results to a percentage of the sum of the ratios:

Personally, I would stick near the top of the table. The lower reaches leave the extreme zones too small – for characters of under 100 hit points, and that’s most of them – a single point would be the difference between one level of injury and the next. Oh, and if you’re wondering why such a precise value as 2.23435 is stuck in the middle of the table, that’s the result that comes closest to delivering a total of exactly 100; without the rounding errors, the total comes to almost 99.992, which is pretty darned close!

Also as a personal note, and while I adore elegant patterns in my tables, I DON’T like this approach. It’s too extreme, there’s too much capacity for no effect at the top (0/a/b zones) and results crowd together too closely at the bottom (c/d/e zones). But that’s a personal assessment, and yours may differ.

Consequences: translating impairment zones into game mechanics consequences

There is a natural approach to assigning a game-mechanics effect to any given impairment level – it’s called the modifier. But from there, things can become a lot more complex and sophisticated.

Modifier Pattern
To start with, consider the amount of this modifier. The simplest approach would be -1, -2, -3, or even -4 per external wound level. (Since there are 5 such wound levels, a -4 per level gives a net -20 at the most extreme level).

But there are non-linear models to consider. -1 cumulative would mean that each wound level increases the change in penalty by 1 at each wound level step – so -1, -2, -3, -4, and -5; the cumulative part means that these compound, giving -1, -3, -6, -10, and -15. This result falls somewhere between the flat -2 and -3 results, and has the additional virtue of reducing the impact at lower wound levels. The result, if applied to the simple linear impairment index is not dissimilar to a flat modifier of about -2-and-a-half applied to the geometric or biased impairment models – and is a lot simpler to implement.

Impairment from internal injuries can be considered a separate issue – perhaps a flat -1 or -2 in addition to the modifiers from external injuries, coupled with a point of bleeding, for each of the two internal injury zones.

Modifier to what, exactly?
Next there is the question of what this modifier is applied to. There are many options:

• Attack Rolls – the character’s mobility is impaired, making his reactions slower in battle.
• Damage Rolls – the character’s physical forcefulness is impaired, so he does less damage in melee.
• Saving Throws – the character is impaired both physically and mentally, making it harder to shrug off environmental complications and spell effects
• Skill Checks – the character cannot move or think as freely as usual, making it harder for him to employ skills successfully
• Initiative – the character slows down in battle
• Hit Points – the character does additional damage to himself by acting forcefully while wounded (once per turn or once per attack)
• Armor Class – the character’s mobility is impaired, making him an easier target in battle
• Movement Rate – the character’s mobility is impaired, slowing his movement

These are all reasonable. And then there is the possibility of combinations – a minus one or two to each of these applications (with the exception of movement rate) would not be terribly significant in isolation but when compounded with all the other penalties represented here, it can be enough to swing the tide of a battle. Multiplying the penalty by 5 would give an appropriate measure for loss of movement (i.e., -5′ per -1 penalty).

Complex Models
Nor do all of these have to receive penalties at the same level, or following the same pattern, or even starting at the same impairment zone. Attack Rolls, Saving Throws and Skill Checks might be -2 per wound level, Initiative and Hit Points might be -1 cumulative for each wound level after Zone ‘A’, AC might be -2 and Movement -5′ per wound level after wound level ‘B’. There are so many combinations and so much flexibility that you don’t really need the complications of a geometric impairment index (which is why I didn’t bother doing a graphic for it).

An even more complex solution is to apply different impairment index models (but the same impairment levels) to different character classes by Hit Dice size. Perhaps your d4 and d6-based classes get the benefit of the more benign Biased Linear Index while the higher hit-dice types – the more active combatants, under normal circumstances – have to cope with the more even-handed Simple Linear Index.

Internal Injuries

These got a mention in the previous section, listing a possible penalty to go with an internal injury, but – aside from defining hit point ranges where a character is at risk – we haven’t yet looked at the ways that a character might incur that risk. As usual, there are a couple of options to consider.

None
This model states that – for the sake of simplicity and game-play – internal injuries are ignored or presumed to be included in the existing external injuries. This is the simplest possible approach.

Automatic
This model states that as soon as a character enters the appropriate injury zone, he receives the appropriate injury. This is the simplest approach that actually includes internal injuries.

Automatic With Save
This is exactly the same as the Automatic check except that the character gets some sort of a saving throw each time they take damage while at risk. I would suggest DCs of 15 and 20 for beta and gamma, respectively, as being appropriate. Note that external injury modifiers may make these saves harder to achieve (modifier to the saving throw) or even trigger a mandatory check (modifier to hit points for strenuous activity).

Automatic With Numeric Threshold
In this approach, a character receives an internal injury if they receive a certain quantity of damage in a single attack, or in a single round. If this is the GMs preferred option, I would suggest thresholds of 5, 10, or 20 points (depending on how severe the penalty is). Note that these thresholds may be different if the character’s condition after the attacks are totaled leaves them in zone beta or forces them into zone gamma.

Automatic With Percentage Threshold
This approach inflicts an internal injury when the damage received in a single blow, or alternatively in a single combat round, exceeds a certain percentage of the character’s hit points. If the simple linear index is being used, the gap between zones is 1/6th of the total hit points, and that seems a reasonable threshold. If a more complex index, then it might be easier to state a percentage outright – 10%, say. Note that this approach permits characters to receive internal damage without serious external wounds if zone 0 is larger than the threshold, and provided that the GM has modified the meaning of zone alpha from “no risk” to “low risk” of internal injuries.

The more likely an injury, the smaller the penalty should be. The less likely, the more draconian you can afford to be. Always bear in mind, when considering such choices, that these penalties are in addition to any conferred by the external injuries system.

Differentiation Of Healing

This is where the fun starts. D&D lists several different varieties of Healing Spell, differentiating them by Wound Type – Cure Light Wounds, Cure Moderate Wounds, Cure Serious Wounds, Cure Critical Wounds, Heal – and I hope I haven’t missed one! Pathfinder preserves this array of choice. When you get right down to it, the only real difference in these spells is the amount of damage they heal – as though they were presuming that injuries totaling a certain amount could be automatically defined as being wounds of a certain degree of seriousness.

In reality, of course, they simply needed a variety of names, and the content of those names is metagame fluff. But that’s what this whole system (and its kindred to follow in other blog posts) are all about – giving same game-mechanics meaning to that fluff, giving it some teeth.

How you apply this differentiation is up to you. The simplest way is for it not to matter – each healing spell does so much healing and that adjusts the character’s position on the impairment chart accordingly.

But there are other, more interesting approaches. You could match each impairment category with a type of damage – Zero and A = light wounds, B & C = moderate, D = serious, E = critical (for example), and state that a lesser form of healing than the one corresponding with the character’s current level of impairment just doesn’t work, or can’t move the character out of that impairment zone. You could state that only Cure Critical Wounds and Heal can restore an internal injury.

You can define Healing potions as CLW only. So you can’t quaff eight or nine or sixteen or whatever to fully recover.

Suddenly, those different spells have a reason to be different, and spell selection for clerics becomes absolutely critical. In fact, a character class that has a Cleric’s combat and spellcasting abilities but a spell list comprising nothing but those Healing spells becomes quite a viable choice (though it would need something else to make up for the other clerical abilities and spells that it was giving up). Call it the Healer?

Even More Fun: Magic! And Class Abilities

By adding another parameter to the handling of damage, Magic can be created by the GM to exploit that parameter. A sword which always inflicts a wound one class higher than the damage would signify. Armor that downgrades impairment levels. A net that impairs a character as though they were one impairment class worse off than they are. A sword that does more damage when the character is seriously impaired, or has some other effect that is triggered only by entry into a given impairment zone (beware of healing effects triggered in this way, they can make a character nearly-invulnerable).

Another potential that these concepts offer are for the creation of class abilities that will further distinguish one class from another. Perhaps some classes take no impairment until zone B, or are treated as being one impairment class better than their current hit points suggest (at least under certain conditions) – A Barbarian’s Rage becomes something more akin to a Berserker attack if he has the latter advantage while Raging, for example.

There’s a general principle here – if you make a change to the game mechanics with a house rule, try to extend it into as many areas as possible. Anything less compromises the uniqueness conferred on the campaign by the presence of that House Rule.

What’s It All For? – The Implications & Benefits

I started this article by suggesting that the reasons for adopting such a system as I have described are flavor. Certainly, they mean that combat takes on a more realistic attribute, where performance in battle is directly compromised by the injuries received. That flavor can also show up in terms of healing and magic items. It certainly gives the GM some direction and foundation for a narrative description of combat, and the flavor that this imparts is reflected back in game mechanics. But there are other implications, some good and some not so good.

Who acts first in a battle become even more important than it was. Having a high Initiative total gives the opportunity to impair a combatant before they even get a chance to strike. For some, that’s a neutral item; for me, that’s a negative (because my NPCs always seem to roll poorly for initiative).

Healing becomes more important, and either a larger slice of the cleric’s role in the party, or the province of a whole new character class. Certainly, the differences between spells that otherwise simply do more or less of the same thing become a lot more significant. That’s both a good thing (the spell definitions) and a bad thing (restricting the role of the cleric).

Critical Hits, which do more damage in a single blow, and hence are more likely to carry a character into an Impairment Zone, also become more than a matter of bookkeeping. That’s a good thing.

Multiple attacks become a more significant step up than a simple multiple of one attack, by virtue of their ability, cumulatively, to force a character into impairment. That’s a bad thing, because it means that the advantages of additional character levels increase at certain points in a character’s history – but that also brings high-level fighters somewhat more in line with the power progression of high-level Wizards, which is a good thing (if you think, as many do, that there is a game imbalance in this area). Wizards become more vulnerable, further eroding any power imbalance; this may provoke more characters to take martial class levels, and that’s probably a bad thing.

Extended combats – ones in which the combatants are closely matched – become more epic. That’s a good thing.

The game in general becomes more lethal, especially to low-level characters and those with small hit dice sizes – that could be either good or bad, depending on a multitude of factors.

Combat becomes something to enter into less lightly and more reluctantly – encouraging everyone to look for non-combat (i.e. roleplay) solutions. Some players will find that a negative, but most players and GMs will view it as a positive.

R&R times between adventures will increase, especially at low- and mid-level, when characters don’t have access to the healing magic they need to recover, and have to lie up until they heal naturally sufficiently for their remaining injuries to be treated magically. That could be good or bad.

The game will certainly be changed, and changed significantly. If your campaign, and the way you want PCs and NPCs to behave, and the tone of adventures and encounters, all support and fit this changed mood, these house rules can be a winner for the whole game. There will be less fantasy and more gritty realism. In a high-fantasy campaign, that can act as a leavening agent; in a mid-to-low fantasy campaign, it can bring the game closer to a historical simulation and less of a comic-book. Is this a change that’s right for you and your game? Yes? No?

Who would have thought that so much impact can be felt from a simple metagame redefinition of the humble Hit Point?

The next part of this trio of articles will look at another option: Hit Points as an index of soft-tissue damage. Part III will consider a high-fantasy variation on the handling of wounds called the Differential Damage Approach (for lack of a better name).