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If infectious disease plays a significant role in your campaign (or just an adventure or two), these rules will be useful. I tried to make designing diseases as fun as using them in a game.
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The Basic Rules |
This is what the common cold looks like: |
When a character comes into contact with a disease, roll against his HT score to see if he catches it. If he doesn't, roll again if he sticks around and keeps exposing himself. If he fails a HT roll and catches it, he starts at level one after an amount of time equal to the disease's interval. For example, if he catches the common cold, he has level-one symptoms 24 hours later. Every character has an immune system, expressed as a unit of time. The normal human's immune system is twelve hours. Once he reaches level one, he starts fighting the disease. He gets to roll against his HT every twelve hours. Every time he makes a successful HT roll, the disease goes back to the previous level. If he makes a roll while he's at level one, the disease is gone. At the end of each interval, the disease moves to the next level of effect. The afflicted character suffers the effects of the level he is on, plus all the previous levels. So, for example, a character at level four suffers the effects of level one, two, three, and four. Often there is a tie between the interval and the immune system roll. If the HT roll and the end of the interval occur at the same time, the disease increases by one level but no effects occur until the character fails his roll. If he succeeds, he drops back a level before the effects occur. If he fails, the disease stays put and he suffers the effects of the level. Every disease can be fully described on a 3 x 5 index card. On the red line at the top, list the name and the interval. On the back, list attack modifiers, restrictions, and notes. Number the blue lines from one to ten and list the effects. That's it! Those are the basic rules. Now let's have some fun and add to them.
Attack Modifiers and Contagion |
The attack modifier is used for the initial HT roll, the roll
to see if the character catches the disease. All diseases are rated
from +10 to -10, with +10 as the most contagious. Modifiers for
contagion are found in the sidebar on p. B133. |
A disease will have more than one attack modifier if it is particularly contagious (or easy to resist) by certain types of character can creatures. For example, leprosy might have a modifier of "+6, +2 for elves."
Restrictions |
Some types of characters and creatures are completely immune to
the disease. This is expressed as "only" or "everyone except."
For example, the disease might be restricted to only women,
everyone except mages, or only members of the Hjarlburg Clan. |
We assume that every disease is restricted to humans, plus all the other types of races available to players in the campaign. The Game Master has to make a judgement in cases of animals (from dogs to dragons) and weird character types (like immortal or bionic characters).
Keeping Track |
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Diseases play out over time, changing the character during the
course of an adventure. To keep things as smooth as possible, the
player and GM must first settle on a specific time when the disease
was contracted. Although this is an abstract figure (who knows
exactly what time your illness began?) it is necessary for
calculating intervals and immune system rolls.The GM keeps track of the intervals. The player keeps track of his immune system rolls. This splits the effort and places each half of the work with the right person. It really reduces the complexity of the rules, as well. The GM gets to monitor the progress of the disease he introduced into the adventure; he can root for it or he might "forget" about an interval roll or two if the sickness starts disrupting the rest of the game. The player of the diseased character, on the other hand, will be eager to roll as often as possible and get rid of the illness. He's not likely to forget when he gets to make his next HT roll, especially if the disease is greatly impairing his character.
Your Health Score |
The HT score plays a large role in all of this. Normally, the
resistance rolls are always based on the character's current
HT. This is especially crucial if the disease's levels of effect
call for a reduction in HT. |
The Levels of Effect |
Very few diseases have an effect for every level. The disease
does progress from one level to the next after each interval
— you never skip — but there isn't always an effect at
every stage of the disease. For example, in the "common cold"
description, levels 3, 5, and 8 have no effect. That means that a
character who reaches level 3 will have the effects of levels 1 and
2. It is only after he reaches level 4 that he adds a new symptom. |
A capitalized effect refers to a specific advantage or disadvantage. In game terms, the character temporarily acquires that ad or disad when he suffers the effects of that level. If an effect cannot be easily summed up with an advantage or disadvantage name (most can) just describe the effect as briefly as possible. The most common effect is a reduction in HT. Other reduction effects are nearly as common, like a loss of ST, Will, IQ, or penalties to sense rolls. Since previous levels still effect the character, these reductions are combined. So, for example, if every level says "ST-2," the character is at ST-2 at level one, ST-4 at level two, and so on. It's easy to forget this and figure that, since each level says "ST-2" that means the character's ST is at -2 during every stage of the disease. Level ten is the climax of effects. If the disease is fatal, just write "death" here.
After Level Ten |
When the disease reaches level ten, it stays there until the
character is cured, he dies, or he becomes part of the group listed
under "restrictions" for the disease. It may be possible for a
character to live the rest of his life with a disease. Just ask any
leper. |
Some diseases will recede or disappear at level ten. This is covered in the options section.
Immunity and Intervals |
The basic premise behind these rules is the connection between
the intervals and the immune system rating. Really nasty diseases
progress at a rate equal to or faster than the average twelve-hour
immunity roll. You might run into a strain of Mad Cow Disease with
a one-hour interval. At that rate, you'll be up to level ten before
you get a single HT roll. |
Then there's the option of having a better-than-average immune system. With a superhuman immune system rating of two hours, you could have a low HT and still beat almost every disease. Immune system ratings range from one minute (for Superman) to one month (for Tree People and other strange creatures with incredibly slow metabolisms).
Susceptibility |
As explained on p. B133, if the initial HT roll to resist
catching a disease is a 3 or 4, the character is immune to it. No
further rolls are needed. |
On the other hand, characters can take the Susceptibility disadvantage, choosing a modifier from -1 to -10 and applying it to a particular disease. The modifier applies HT rolls to resist catching the disease and fighting it. The character point value is 2 points per -1. If the disease is likely to be encountered in every adventure, double the value. If it is likely to come up once every two or three adventures, the value stays the same. If the disease will not be encountered more often than every third adventure, the disadvantage is a Quirk. Once a character has suffered from a disease and has recovered, the character is immune to it. He could encounter a new strain, of course. Or, he might have suffered from a bacterial infection that the body cannot inoculate. Handling sewage or toxins, for example, can repeatedly sicken the character.
Immunity to Disease |
This advantage gives the character a +10 to contagion rolls
and immune system rolls. In a disease-based campaign
(imagine that), this would be different — in that case, the
advantage would be level-based, with each +1 at about 2 points
apiece. |
I base the +10 figure on the panimmunity sidebar in the TL 12 chapter of GURPS Ultra-Tech. Level-2 panimmunity, is listed there as +8 against disease for $5,000 and 5 character points. Level-3 panimmunity is the equivalent of Immunity to Disease.
Altering Your Immune System |
Alternations to a character's immune system are either
temporary or permanent. The permanent changes warrant a notation on
a character sheet, with a possible character point value. But more
often the change is the result of circumstances, usually prompted
by the disease, making it temporary. |
For example, a character with the common cold might stay in bed, drink fluids, and take some over-the-counter medication. The result is a boost to his HT (maybe +1 or +2) and a change in his immune system from twelve to eight hours. Once he gets out of bed (presumably after he's no longer ill) his immune system changes back to its normal rate. There are dozens of ways to alter your immune system with magic, drugs, psionics, and technology. I'll cover those later, probably next issue. I'll also print the character point values for different immune system ratings later. I'll tell you right now that's it's nothing to worry about. Even the weakest or strongest immune system matters very little outside a disease-based campaign.
Rule Changes |
There is one change in the Basic Set rules. At the
bottom of p. B133, it says that characters typically make a HT roll
against a disease every day. I changed this, using the immune
system rating of twelve hours, to twice a day. |
The Basic Set also says that diseases reduce your HT score and, when you've returned that attribute to its original level, you've recovered. I've added to that. Now diseases can do lots of other things, as well.
An Example |
Dr. O'Toole, a female physician with an average HT score, meets
a patient who has the common cold. She rolls to resist it and
fails. Twenty-four hours later (we'll say at 5 pm) Dr. O'Toole is
at level one. Now her HT is 9. |
At 5 am, she rolls against her HT, rolling a 14. She failed and retains the disease. At 5 pm, 48 hours after she first contracted it, 24 hours since the first symptoms appeared, she moves up to level two. But, since she gets a HT roll at the same time, she rolls before the effects manifest. She rolls a 10, a failure, and she now suffers from congestion. In addition, she still suffers the effects of previous level(s), so her HT is still at 9. At 5 am, she gets another HT roll. She rolls a 15, a failure. Still at level two. She takes some medication and sleeps for ten hours, trying to overcome her illness. At 5 pm, at the end of the third day, while she is sleeping, she moves to level three and gets a HT roll before the effects occur (although there are no effect at level three for the common cold). She rolls a 10, another failure. She stays at level three. The GM decides that her immune system is now down to eight hours, thanks to the sleep and medication. Eight hours after 5 pm is 1 am. At that time she rolls, gets a 4, and moves back to level two. Her next roll is at 9 am. She rolls a 9, barely making it. She's down to level one; she's no longer congested. She takes some more medication and gets plenty of rest, retaining her eight-hour immune system. At 5 pm at the end of the fourth day, she moves up to level two. Before she gets congested again (before she suffers from the effects), she gets her HT roll. She rolls a 5 this time, dropping back down to level one. Eight hours later, at 1 am, she rolls an 8 and is cured. She had the common cold for four days and eight hours. Without the medication and bed-rest, she would have had it longer.
Options |
The most significant option is to alter the interval for a
particular disease. The standard is 24 hours, giving the victim two
HT rolls per level and one day between catching the disease and the
first signs of sickness. |
The interval can range from thirty minutes to thirty days. Any interval less than twelve hours means the disease will increase to a higher level before the average victim gets a HT roll. Multiply the interval by ten and you'll know the minimum amount of time required for the disease to reach its maximum effect. Keep in mind that a character who stays in bed and takes medication will reduce his immune system rating somewhat, by one to four hours (depending on the GM's judgement). The following options are divided into two sections. The first should be committed to memory easily because they are the most obvious alternatives that come to mind. The second set is more imaginative and unusual.
Common Options |
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Long-Term. This disease gets harder and harder to cure as
it progresses. After catching it, every HT roll is penalized by an
amount equal to the current level.Short-Term. The disease is easier to recover from as it progresses. After catching it, every HT roll gets a bonus equal to the current level. Tenth-Level Remission. Once the disease reaches tenth level, it starts to recede. At the end of each interval, it returns to the previous level, steadily declining. Tenth-Level Recovery. Once the disease reaches tenth level, it stays there for one interval and then vanishes. Recovery Ceiling. If the level stays put for three intervals in a row, the disease cannot advance further. It can stay at that level or decline, but it cannot get worse. (You can also use a two-intervals-in-a-row option.) Permanent Effect. Any effect marked with a "pound sign" — a # symbol — is permanent. Once the character reaches that level, the effect sticks, even if he drops to a previous level later on. Reversing this effect requires special attention separate from the cure of the disease. For example, chronic dysfermia lists "HT-1 #" as its level-ten effect. Once the character reaches that point, he suffers a permanent reduction in HT. Even if he is cured, that HT score is reduced. Single-Level Effect. If a level is marked by an asterisk, the character suffers those effects only when he is at that level. So, if level four is marked with an asterisk and the character is at level six, he has the effects of levels one, two, three, five, and six. If he is at level four, he has the effects of levels one, two, three, and four. It is pointless to mark level ten with an asterisk. If you mark levels one through nine, the character will suffer only one effect at a time. Contagious Carrier. The attack modifier is based on the infected carrier's current level. For example, if the disease is acquired from a victim who is currently at effect level four, the attack modifier is +4. Half-Strength Contagious Carrier. With this option, the attack modifier is half the carrier's current effect level, rounded down. For example, if the carrier is at level six or seven, the attack modifier is +3.
Additional Options |
Half-Value Long-Term. Like the long-term option, but only
half the level (round down) is applied to the roll. So, every HT
roll is at -1 at levels two and three, at -2 at levels four and
five, and so on. |
Half-Value Short Term. Like short-term, but at half the normal bonus to each HT roll. Dormant. After catching the disease but before reaching first level, the disease enters a dormancy period. It's in the character's body, but it hasn't been triggered yet. The GM must decide if the trigger is an event, a time period, or both. The time period can be a set time or a die roll. Once the dormancy ends, the character starts at first level and the disease proceeds normally. (You could also make the trigger unknown, like the onset of AIDS.) Virulent Strain. The character starts at a level equal to half the amount by which he failed his contagion HT roll (round down). For example, if the character needs an 8 or less on the initial HT roll and he rolls a 15, he failed by 7. This is 3.5, rounded down to 3, so he starts at the third effect level. Extremely Virulent Strain. As above except the full amount of the failure is used. (So, in the example, the character starts at level seven!) Special Cure. There is a special substance, circumstance, or event that will cure the afflicted character. After defining the cure, decide if it (a) makes the disease go into remission at a rate of one level per interval, (b) makes the disease disappear at the end of the current interval, or (c) the cure makes the disease instantly disappear. Special Protection. This is like the special cure option, but the substance, circumstance, or event prevents the disease from progressing beyond a certain level. For example, a special drug might prevent the disease from advancing beyond level five. Or, if the character stays underground for 24 hours, the disease can progress no further than the current level. Level-Based Intervals. If you list a unit of time in parentheses on a particular level of effect, that is the interval between that level and the next. For example, suppose the interval for the disease is 24 hours. At level six, you write "ten hours" in parentheses. This means that it takes a day between levels five and six, ten hours between levels six and seven, and a day between levels seven and eight. You could have a different interval between every level. You could also give a group of levels the same interval — maybe everything from level five onward is eight hours. Suspended Interval. Specify a condition that halts the disease. As long as the condition persists, the current interval never ends. Once the condition ends, resume the interval. Interrupted Interval. An action or event causes the interval to start over again at that moment. If the character is lucky and/or resourceful, he may be able to interrupt the interval often enough to avoid any change. Reduced Interval. A particular substance, condition, or event reduces the interval, making the disease progress faster. Unless otherwise specified, the interval resumes when the condition or event ends, or when the substance runs out. But the change could be permanent. Extended Interval. Like the previous option, but the interval is lengthened, making the disease progress more slowly. Random Interval. When a character catches the disease, roll dice to determine the interval. Note the unit of time used. For example, the interval might be 3d days, 1d hours, or 9d minutes.
Designing Diseases |
When you design a disease, advantages, disadvantages, and
spells are your best friends. You can whip a new disease together
in thirty seconds by simply listing a handful of ads and disads in
the effect levels, adding an interval, and brainstorming some kind
of restriction. Name it, consider an attack modifier, and you're
done. |
Spells can be used for effect level ideas that can't be described with an advantage or disadvantage. For example, you can thumb through the College of Mind Control and come up with the following disease:
Not only are these lists good sources of ideas, they may be necessary — if the effect you want is already fully developed somewhere in a GURPS book, you'll want to use those rules instead of making up your own. For example, the rules for having one eye have already been written. Rather than list the effects of one eye in the level description, just use One Eye as the effect. If someone wants to find out the details, let them refer to the book.
Types of Disease |
There are a variety of basic types. There's the known diseases
— polio, tuberculosis, leprosy, herpes, etc. You could research
these (possibly by contracting them and taking notes) or you can
just wing it. |
Then there are the gross-outs, the ailments known best for their disgusting effects. You can do the withering disease, the disfiguring syndrome, and the infamous blood-shooting-out-of-every-orifice virus. For a more subtle approach, try a mental disorder. A character might catch something that alters his mind, not his body. This ranges from Alzheimer's to full-blown lunacy. Hereditary diseases are designed by listing a family name under "restrictions." Some diseases are curable; others are not. Some incurable diseases, like herpes, are inconvenient but not fatal. A fatal and incurable disease such as AIDS, Ebola, and cancer will strike fear in all characters and have major effects on campaign societies.
Coming Up With Ideas |
Start with a name, a type, or a list of effects. Effect lists
can be brainstormed. This is especially useful when you're trying
to create a disgusting disease — just list every gross thing
you can imagine and pick the best five, six, or seven as effects. |
If you start with a name, it will suggest most of the effects. You might start with a funny or pun-based name like "the computer virus" or "the travel bug." Look through the list of options. There's plenty of ideas there.
Requirements |
Every disease must have a level-one effect and a level-ten
effect. Every disease must have an interval between thirty minutes
and thirty days. Every disease must have a name. |
Everything else is optional.
Designing Effect Levels (the Symptoms) |
Remember that, unless an effect is marked by an asterisk, it
stays while the character suffers from higher levels. Effects are
cumulative. The most common mistake when designing effects is to
list attribute penalties like this: |
Lvl 1: HT-1 Lvl 2: HT-2 Lvl 3: HT-3 Lvl 4: HT-4
The designer meant that the victim of the disease loses
a point of health at each level. But, according to the rules, the
character is at HT-3 at level two, HT-6 at level three, and HT-10
at level four.
headache
New Disadvantages |
Disease victims can acquire new disadvantages after they recover. For example, if
the character nearly dies from malaria contracted from insect
bites, he might acquire a mild phobia of bugs. He might get an
Obsession, a Secret, a Duty to help others who have suffered the
same fate, or become Addicted to special immunity pills. Discuss
this with the player first — if he just hates the idea,
drop it. |
Names |
Start by thinking of (or writing down) the names you already
know. There's Lou Gerihg's Disease, named after the most famous
victim. There's Ebola, named after the river in Africa where it was
first discovered. There's "the common cold," an illness that
seems to be named after the temperature outside when you catch it. |
Spinal meningitis has a name that makes you want to consult a general medical reference for ideas. You can easily pair a technical name for a part of the body with another technical "condition word" — esophagal delimitation, cognitive inversion, vaginal spasmania, and transdermal migratory syndrome. For real fun, make up a long technical name that works as an acronym, like acquired immune deficiency syndrome as AIDS. For example, you could call your new disease regressive internal serum complex, or RISC. And every name can be defined with a secondary word like RISC-a, or herpes simplex. You can add the word "chronic" to any disease and make a whole new ailment.
Sample Diseases |
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