Environmental Hazards & Conditions

Copyright © 1998-2005 Ken St-Cyr. All rights reserved. This is a work in progress.

Movement & Travel

When simulating movement over terrain, slope, roughness, vegetation, mode of travel, and fatigue can all play a part in determining how long travel should take. It's not enough to know how fast a traveller will move if you don't know the exact path taken. Vegetation must be coped with, slopes climbed or cautiously descended, cliffs and boulders negotiated, etc. Then, of course, one does not typically travel overland in a straight line.

One approach is take estimated averages and introduce some randomizers. There are steps to this: take the average straight-line speed of the traveller (movement rate), then figure a number to represent the costs of negotiating obstacles and slopes (movement cost), then modify the result plus or minus a few percentage points (like 4d6-14). The random modifier can be safely ignored, since we are dealing with averages.

Movement Rates

Walk Jog Run Sprint
Human 5 10 15 25
Pack Animal 6 12 18 30
Battle Mount 8 16 24 40
Riding Animal 10 20 30 50
Racing Animal 15 30 45 75
- Movement rates in kilometers per hour.

Movement Costs

Dry GroundMud/Snow
Terrain RoadOff-RoadRoadOff-Road
* - Maximum pace is Run
** - Maximum pace is Jog

To find out how much distance (in kilometres) a traveller can cover in one hour, divide movement rate by movement cost. For example, a human typically walks at 5 km/hour. Over dry ground on a road through wooded hills (forest/rough) he can cover 5/2, or 2.5 km, in one hour.

To find out how long it will take to cover a given distance (over homogeneous terrain), divide movement cost by movement rate. The same human from the example above, would take 2/5, or 0.4 hours (24 minutes) to cover 1 km of ground.

Travelling incurs one physical fatigue level over a period of time determined by load — Unencumbered: 4 hrs; Burdened: 3 hrs; Loaded: 2 hrs; Heavily Loaded: 1 hr. A half hour of rest will recover this fatigue.


Towns are described according to their population, area, garrison, market type, and fortifications. Area may be calculated by dividing the population by population density, where typical values for density range from 1 (dispersed rural) to 300 (dense urban) persons per hectare.

The table below gives some generic settlements with typical values for market type, defenses, and percent of population available for the militia. These values should be adjusted to fit the characters of specific settlements.

Class Pop Mkt Def Guard Watch
Hamlet 50 D C0/W1 0 0
Village 500 D C0/W2 0 0
Small Town 1000 C C0/W3 4 10
Small Town 1500 C C0/W3 6 15
Medium Town 2500 C C0/W3 10 25
Large Town 5000 B C1/W4 20 50
Large Town 8000 B C2/W4 32 80
Small City 10,000 B C3/W4 40 100
Small City 12,500 B C4/W4 50 125
Medium City 25,000 A C4/W5 100 250
Large City 40,000 A C4/W5 160 400
Large City 60,000 A C5/W5 240 600

Market Type

The market type of a settlement is a description of the quality and modes of transportation of goods to other markets. The combination of market type and population is a rough measure of the relative availability of products and services in that settlement. People in a town of market type A will have available to them nearly anything for a price; whereas a town of market type X will only have locally produced goods available, and probably only for bartering.

AMaritime. The settlement has a sea port and fields ships that trade overseas with other dominions and has a solid road and river network for overland trade.
BCoast & Road Trade. The settlement has a sea port that can handle coasters for local sea trade, possible river barges, and a road network. Alternatively, the settlement has a sea port that fields ships that trade overseas, but lacks a supporting road and river network.
CRiver & Road Trade. The settlement has no sea trade, but has a good road & river network.
DPoor Road Trade. The settlement does not engage in sea or river trade, and has only a poorly maintained road network.
EFrontier Trade Post. There is a trading place here, but routes to it are trails only and unmaintained.
XNo Trade. The settlement does not trade with other places of habitation.

Town Defenses

Town fortifications are rated in two areas: walls and citadels.

W5Concentric Stone Walls The town is surrounded by two or more rings of walls. A highly fortified town would fill the area between the walls with military grounds.
W4Fortified Stone Wall. The town is surrounded by a battlemented stone wall reinforced with towers.
W3Stone Wall. The town is protected by a simple stone wall.
W2Palisade & Earthworks. The town is surrounded by a palisade and ditch, possibly with additional ditches and berms.
W1Earthworks. The town is surrounded by one or more ditches and berms.
W0No wall. The town is unprotected by fortifications.

C5Multiple castles. A heavily fortified settlement with several castles, each protecting key points.
C4Large castle. The citadel is a large castle with a large keep, several layers of defense, and many towers.
C3Medium castle. The citadel is a mid-sized castle, with a keep and eight to ten towers.
C2Small castle. The citadel is a castle with a keep, four to six towers.
C1Shell keep. The citadel is a simple stone enclosure with a great tower.
C0No citadel. The settlement has no central fortification.

Light Conditions

The following table gives visibility ranges in meters for various light and weather conditions. Light obscurement includes rain, light fog or snowfall. Heavy obscurement includes heavy rains, heavy fog, or blizzard. Dense obscurement is thick smoke or peasoup fog.

Light Level

Visibility range in meters. Assumes a small moving figure, or a large stationary object. Double for large moving objects, halve for small stationary objects.

Missile ranges are based on conditions of unlimited visibility. When visibility is at 1000 meters, cut missile ranges in half. Adjust missile ranges at other levels of illumination by proportionally (i.e., 1/4 at 500 meters, 1/20 at 100 meters, etc.)

General Effects

An effect is rated in levels, e.g., Confusion-3. Reduced task effectiveness means that every level of effect modifies the character's task roll by -1, up to 5 points. Minimal effectiveness means the task roll is reduced by 7 points.

Task bonuses are likewise +1 per level of effect, to a maximum of 5 points.

Delirium: Loss of judgment. The character suffers reduced effectiveness at mental tasks and may be unable to make a sensible choice of action.

Fear: Feelings of dread, including awe, revulsion, and panic. Fear can be resisted with willpower. Characters with fear move at twice normal rate but fights defensively only. Extreme fear can cause effects similar to narcosis.

Mental Fatigue: Drowsiness. The character suffers minimal effectiveness at all mental tasks, and reduced effectiveness at physical tasks.

Narcosis: Loss of sensation or, in extreme cases, paralysis. The character's effective perceptivity is reduced. Mild effects reduce initiative and effectiveness at physical tasks. Paralyzed characters may perform no physical action.

Physical Fatigue: Weariness or weakness. The character suffers minimal effectiveness at all physical tasks, and reduced effectiveness at mental tasks. Furthermore, movement rate is reduced to 10% walking rate, and no faster pace may be attempted.

Sedation: Relaxation of muscles, enervation, emotional depression. The character suffers an initiative penalty and is otherwise treated as physically fatigued.

Spasms: Involuntary muscular movements. Mild effects reduce the effectiveness of all tasks requiring agility or dexterity. Extreme effects means the character may perform no actions.

Stimulation: Energized, excessive stimulation may cause jitters. The character gets an initiative bonus and increased strength and endurance, but suffers double fatigue effects when the stimulant wears off.

Suffering: Afflicted with pain, irritation, or other discomfort, such as nausea. Suffering characters are distracted such that all mental and physical tasks are at reduced effectiveness. Characters may attempt to overcome the effects of suffering with willpower.

Vertigo: Dizziness, disorientation, or loss of balance. Dizzy characters suffer reduced effectiveness at all physical and mental tasks. Furthermore, movement is subject to random direction.

Hunger & Thirst

Food and water may be carried, or may be acquired whilst travelling. The task for foraging and hunting is based on Survival and Perception. The cost in time is the same as if the character were loaded with the equivalent amount of food and water.

Food Requirements: An average person undergoing moderate activity eats about 1 kg of mixed foods each day. Strenuous activity doubles this. Characters eating below the required food for a day receive one level of physical fatigue (see below) each day, until minimum daily food requirements are met.

Water Requirements: Normal requirement in fair weather and moderate activity is 2 litres of water. A person can live with only 1 litre before suffering penalties. Except under the hottest conditions, a person can survive for about a week without water. Characters going without minimum requirements for water receive one level of physical fatigue each day, until minimum daily water requirements are met.

Pits, Snares, & Rockfalls

Falling incurs bash damage. A rockfall or the like is crush damage. There are different types of snares, capable of incurring a variety of damage types.

When a character hits the ground from a fall, he can try to mitigate damage by spreading the impact. Look up the Agility Check target on the table below. Roll 3d6 + agility modifier + tumbling skill level and try to beat the target. Success means the damage may be divided between two hit locations; failure means the impact is concentrated on one hit location. Additional levels of success divides the impact among additional hit locations on a one-for-one basis.

Impact is determined by rolling the damage dice indicated on the table. Use the Basic Damage table because falls are non-penetrating.

Base Impact Damage
3 m5154d6-3
6 m10205d6-4
9 m15256d6-5
12 m20307d6-6
15 m25358d6-7
18 m30409d6-8
21 m304510d6-9
24 m305011d6-10
Example: Lossult, who has an AGL of 14, falls down a nine-meter deep pit. The AGL check is 15, Lossult's AGL bonus is +1. He rolls 3d6 and adds 1. If his adjusted roll beats a 25, the impact is divided by two and applied to two hit locations; if he fails, all of the impact is applied to a single hit location. Say that poor Lossult fails with an adjusted roll of 9. Now he must determine the injury he receives. First he rolls 3d6 on the hit location table, gets an 11, and discovers he has fallen on his chest. Second he rolls 6d6-5 for impact and gets an 21. From the Basic Damage table, he finds that, since he is size 10 he has received a critical injury. The fall has killed him.

Falling damages represent landing on a hard surface. Different surfaces modify the damage roll. The figures assume there is sufficient depth to the material to absorb impact (about one-sixth distance fallen for water; less the more solid the material).


Additional damage from variant surfaces such as spikes, broken glass, etc, should simply alter the damage type to be instead of or in addition to the bash damage.

Swimming, Drowning, & Asphyxiation

Suffocation is the cutting off of an air supply to the lungs. Asphyxiation occurs when oxygen levels in the blood are too low and carbon dioxide too high. (Asphyxiation occurs with suffocation). In game terms, this is a life-threatening fatigue event which may lead to internal organ damage — particularly the brain. Unconsciousness occurs before brain damage, which occurs before death.

At the end of every minute the character suffers an attack versus his endurance on the Asphyxiation table. The attack starts at +0 the first minute, and increases by 3 points every minute thereafter.

Superficial (5)Fatigue-1
Minor (10) Fatigue-2
Serious (15) Fatigue-3
Critical (20) Unconsciousness
Deadly (25) Brain Damage


Excessive heat or cold may incur a physical fatigue cost, hourly or every ten minutes depending on conditions. Roll 3d6, add 5 for freezing cold or sweltering heat, and subtract the victim's endurance modifier. Apply one level of physical fatigue per severity level, plus any additional damage indicated by the Exposure table.

Temperature RangeFatigue Intensity
Freezing (below -15)+5Every 10 min.
Cold (-15 to 0)+0Hourly
Moderate (0-30 C)N/AN/A
Hot (31-35)+0Hourly
Sweltering (36+)+5Every 10 min.
- Temperatures in degrees Celsius.

Superficial (5)Fatigue only
Minor (10)Delirium
Serious (15)Vertigo
Critical (20)Unconsciousness


Burn damage from fire is rated according to the temperature of the fire, which is a property of the combusting material.

Burning MaterialDmgNotes
Lamp Oil +6Liquid
Natural Gas+6Gas
Tar +5Torch material
Lava +5
Charcoal +3
Coal +2Very smoky
Wood +1

Penetration values are not used. Armor will not protect against fire, but wet or icy clothing will.

Apply fire damage to each hit location exposed. A splash will hit 1d6 locations. Damage is applied each round as long as the victim remains in contact with the fire.

Fires may also inflict asphyxiation damage from smoke.

Corrosive Substances

Burn damage from corrosive substances (acids and alkalis) is rated according the the pH of the chemical. Damages below assume concentrated forms of the chemicals.

Stomach acid+4Hydrochloric acid
Lye+4Sodium hydroxide
Oil of Vitriol+1Sulfuric acid
Nitric acid-1Toxic fumes
Tartaric acid-4Fruit acid
Formic acid-4

Apply corrosive damage to each hit location struck. Armor may protect against corrosive attacks, but has a chance of being ruined. Penetration differs, because no impact is involved. A corrosive substance will penetrate armor on beating a target of 8 if 25% covered, 10 if 50% covered, 12 if 75% covered, or 14 is 90% or better covered.

Damage is applied each round as long as the victim remains in contact with the substance.

Poisons, Diseases, & Drugs

Harmful substances have numerous effects on the body. The primary purpose of these rules is to provide mechanics for dealing with the various effects, leaving descriptions of the actual substances into the realm of the world designer. Besides, a good medical reference will do a better job of describing poisons, diseases, and drugs than this game could ever hope to do.

When describing a harmful substance, the effects, the intensity of the effects, and how the effects are applied must be considered. Onset time is how long after a victim comes in contact with the substance that the effects are applied. Period is the frequency of which the effects are accumulated, if at all, while the substance is active. Duration is the total time the substance remains active within the victim's body.

IntensityOnset TimePeriodDuration
2Minutesper secondMinutes
3Hoursper minuteHours
4Daysper hourDays
5Weeksper dayWeeks


A poison is any substance that can cause harm by contact, ingestion, or inhalation.

Poison Onset TimePeriodDuration Effects
Alcohol InstantOnceHours Delirium, Mental Fatigue
Arsenic 30 min.Per hourHours Narcosis, Physical Fatigue, Suffering, Vertigo
Botulism HoursPer dayDays Delirium, Narcosis, Suffering
Cyanide InstantPer hourMinutes Asphyxia
Lye InstantPer dayDays Suffering
Strychnine MinutesOnceMinutes Spasms
Toadstool HoursPer dayDays Narcosis, Suffering


Modern medicine uses the term disease broadly. Here, we specifically mean communicable diseases.

Infection — target to beat to avoid infection after contact with an agent (carrier); add endurance modifier to roll.
Incubation — period that elapses before symptoms appear
Duration — how long the disease lasts after symptoms appear; chronic means it lasts until cured
Recovery — additional time required to recover after the symptoms have disappeared

Consumption: Tuberculosis of the lungs. Infection: 7. Vector: Airborne. Incubation: 4-12 weeks. Duration: 5 years. Effects: Physical Fatigue, Suffering.

Dysentery: Diarrhea of blood and mucus from the bowels. Infection: 9. Vector: Contaminated food or water. Incubation: 1 day. Duration: 1-3 days. Recovery: 7 days. Effects: Suffering.

Leprosy: Bacterial disease of the skin and nerves. Infection: 5. Vector: Contact. Incubation: 1-12 years. Duration: chronic. Effects: Necrosis.

Pneumonia: Inflammation of lung tissues. Infection: 8. Vector: Airborne, contact. Incubation: 1-3 days. Duration: 5 days. Recovery: 9 days. Effects: Spasms, Suffering.

Rabies: Narcosis, hydrophobia, delirium. Infection: 9. Vector: Animal bite. Incubation: 3-8 weeks. Duration: 2-6 days. Effects: Fear, Narcosis, Stimulation, Suffering.

Syphilis: Sexually transmitted disease. Infection: 8. Vector: Sexual contact Incubation: 3 weeks. Duration: Chronic. Effects: Physical Fatigue; reduces health and shortens lifespan.


First Aid: First aid has two objectives: to prevent an injury from becoming more severe, and to prevent the injury from becoming infected. Any wound worse than superficial will become more severe unless treated within the time specified by first aid procedures.

Infection: For each wound suffered, the victim must roll a 7+ on 3d6 to avoid infection. An infection prevents a wound from healing.

Basic Healing Rate:

All wounds heal simultaneously, except that wounds less than serious are not recovered until and critical or serious wounds are reduced to minor status. Basic healing rates assume flesh damage. Double healing times for bone damage:

Wound Level ChangeBase Time to HealFirst Aid Target
Critical to Serious2d6 days25
Serious to Minor6d6 days18
Minor to Superficial4d6 days13
Superficial to Healed2d6 days10

Endurance modifies healing by altering the numbers of days required to heal each stage. Positive modifiers reduce healing time, negative modifiers increase it. These are the values to use if the character is unattended by a physician, but has adequate food and shelter. Assuming successful task rolls, a physician reduces the time by 1 day per die rolled. No modifiers to healing rate may reduce the total of all dice to less than the number of dice rolled.

Note: A critical wound does not mean the individual is in “critical condition” as per modern usage. One would not expect someone in critical condition in a medieval environment to survive for long. Basically, critical condition ends as soon as it has been determined the character will survive a life-threatening wound or injury.

Selected Works

Benenson, A. Control of Communicable Diseases Manual. (Washington, D.C., 1995)

Stevens, S and A. Klarner. Deadly Doses: A Writer's Guide to Poisons. (Cincinnati, 1990)

Last modified Sun, Jul 31, 2005
Next | Contents | Prev