Metric Conversions

The most common conversions needed by most GMs are:

• Feet and yards: Use 30 cm for feet, or 1 m per 3 feet. Use “metre” to replace all occurrences of “yard”.
• Pounds of weight: For small or imprecise quantities, divide quantities by 2 to get kilograms.

For any conversions not covered by this document, the following conversion chart is an expanded version of the one supplied on p. B9.

Temperature: When dealing with changes in temperature, one Fahrenheit degree is 5/9 the size of a degree Celcius. So a change of 45°F is equal to a change of 25°C. To convert actual thermometer readings, subtract 32 from the Fahrenheit temperature and multiply the result by 5/9. So 95°F is 5/9 of (95-32), or 5/9 of 63, or 35°C. Note that this has the effect that -40°F is equal to -40°C.

The standard scale for temperature is relative to the theoretical “absolute zero”, -273.15°C, represented as 0 kelvin (symbol: K). A change of 1 K is the same size as a change of 1°C.

Radiation: The SI unit of absorbed radiation is the gray (symbol: Gy): one joule of radiation energy absorbed by one kilogram of matter. A radiation absorption of 1 Gy is equivalent to 100 rads.

Pressure: The SI unit of pressure is the pascal (symbol: Pa): one newton of force per square metre. One standard atmosphere (atm) of pressure is equivalent to about 100 kPa.

Physical Constants

GURPS Basic Set does not have a particular section for physical constants, but they are mentioned in various places. Some important physical constants used in GURPS:

Absolute zero (0 K)

The thermodynamic point where no more heat can be removed from a system.

• Game metric: 0 K = -270°C, or -300°C for more coarse measurements.
• Actual metric: 0 K = -273.15°C.

Speed of light (c)

A definition (not measurement!) of the speed of light travelling in a vacuum.

• Game metric: c = 300 000 000 m/s = 1.0e9 (= 1 000 000 000) km/h.
• Actual metric: c = 299 792 458 m/s = 1 079 252 848.8 km/h.

Light-year (ly)

The distance light travels in a vacuum in one Julian year.

• Game metric: 1 ly = 9.5e15 (= 9 500 000 000 000 000) m.
• Actual metric: 1 ly = 9 460 528 404 879 000 m.

Astronomical unit (AU)

The mean distance of the Earth’s orbit from the Sun.

• Game metric: 1 AU = 1.5e11 (= 150 000 000 000) m.
• Actual metric: 1 AU = 149 597 870 691 ±30 m.

Parsec (pc)

A distance such that a body, at that distance from an observer on Earth, appears to travel one arc second in the sky as the observer moves across the diameter of the orbit of Earth.

• Game metric: 1 pc = 3.0e16 (= 30 000 000 000 000 000) m.
• Actual metric: 1 pc = 30 856 775 800 000 000 m.

Gravitational acceleration (g)

The standard acceleration due to gravity at the Earth’s surface.

• Game metric: 1 gravity = 10 m/s².
• Actual metric: 1 gravity = 9.806650 m/s².

Standard atmosphere (atm)

The mean sea level atmospheric pressure on Earth (at the latitude of Paris, France).

• Game metric: 1 standard atmosphere = 100 kPa.
• Actual metric: 1 standard atmosphere = 101.325 kPa.

Specific Rules Changes

The bulk of this document presents specific local changes to the GURPS rules to allow use with the modern metric system. Every change gives the page number to which that change applies. These are presented in two forms:

• Specific instructions for how to transform the text at that location. This will usually specify replacing a unit, re-calculating quantities, or both. You should scan the text at the specified location and perform the transformation.

  Such instructions are presented in normal text.

• Replacement text to be used verbatim at the location. To make it easier to find and replace the original text, the suggested replacement text will strongly resemble one or more sentences at the specified location. Simply substitute the recommended text for the sentences they resemble, with all adjacent text unchanged.

  Such replacements are presented like this.

Basic Lift

Basic Lift is the maximum weight, in kilograms, you can lift over your head with one hand in one second. It is equal to (ST×ST)/10 kg. If BL is 5 kg or more, round to the nearest whole number; e.g. 16.9 kg becomes 17 kg. The average human has ST 10 and a BL of 10 kg.

Basic Move

±5 points per ±1 metre/second

Replace all occurrences of “yard” with “metre”.

Basic Lift and Encumbrance Table

This table summarises Basic Lift and encumbrance levels for ST 1-20.

Build Table

Penetrating Vision

Each level of this advantage allows you to see through up to 150 mm of normal matter.

Pressure Support

Every character has a “native pressure”. For ordinary humans, this is the pressure of Earth’s atmosphere (100 kPa). A native pressure other than 100 kPa is a 0-point feature, but if you can survive for a prolonged period of time at a wide range of pressures, you have an advantage.

Regeneration

Heals Radiation: You shed accumulated grays at 1/10 the rate at which you heal missing HP. For instance, Regeneration (Regular) removes 0.1 grays per hour.

Radiation Only: As Heals Radiation, but you only shed grays – you do not heal HP.

Scanning Sense

Radar: Base range is 2 kilometres.

Imaging Radar: Base range is 200 metres.

Ladar: Base range is 200 metres.

Sonar: Base range is 2 kilometres underwater. Sonar is much less effective in air: range is only 0.2 metres multiplied by air pressure in kPa. Sonar is completely ineffective in vacuum.

Snatcher

The item must be able to fit in one hand, and cannot weigh more than 2 kg.

Less Weight: Your weight limit is lower than 2 kg.

Telecommunication

Infrared Communication: Base range is 500 metres in a direct line of sight.

Laser Communication: Base range is 80 kilometres in a direct line of sight.

Radio: Base range is 15 kilometres.

Temperature Control

You can alter the ambient temperature. Heating or cooling is limited to 10°C per level, and occurs at a rate of 1°C per level per second of concentration. You can affect a two-metre radius at a distance of up to 10 metres.

Temperature Tolerance

Every character has a temperature “comfort zone” within which he suffers no ill effects (such as FP or HP loss) due to heat or cold. For ordinary humans, this zone is 30° wide and falls between 2°C and 32°C. For nonhumans, the zone can be centred anywhere, but this is a 0-point feature for a zone no larger than 30°. A larger zone is an advantage. Each level of Temperature Tolerance adds HT/2 degrees to your comfort zone, distributed in any way you wish between the “cold” and “hot” ends of the zone.

Warp

Distance: Distance penalties appear on the table below. If actual distance falls between two values, use the higher.

Add an additional -1 for each 10× increase in distance.

You can use Warp to evade attacks in combat. Once per turn, you may teleport to any location you can see within 10 metres, instantly. This is considered a dodge. Of course, the IQ roll will be at -10 for instant use, so you might want to spend FP to improve your odds!

Damage Modifiers

Radiation (rad): The attack irradiates the subject. Roll damage normally, but whether or not the attack penetrates DR, it inflicts 0.01 gray per point of basic damage rolled. See Radiation for effects.

Cold-Blooded

After 30 minutes in cold conditions (or one hour if you have any level of Temperature Tolerance), you get -1 to Basic Speed and DX per 5° below your “threshold temperature” (see below). At temperatures below 0°C, you must roll vs. HT or take 1 HP of damage. Warm clothing gives +2 to this roll.

You “stiffen up” below 10°C: -5 points.

You “stiffen up” below 20°C: -10 points.

Long-Distance Modifiers

Use these modifiers for Information spells that work over long distances, such as “Seek” spells. Certain advantages also use these range penalties. If the distance falls between two values, use the higher.

Add another -2 per additional factor of 10.

Earth to Air

Cost: 1 to transform 30 000 cubic centimetres of earth/stone to air, giving enough air for one person to breathe for 1 minute. To transform larger quantities of earth/stone at once, the cost is 15 per 2 cubic metres.

Shape Earth

Cost: 3 per 4 cubic metres of earth shaped (minimum 2); half that to maintain; round all costs up.

Earth to Stone

Cost: 7 per 3 cubic metres (minimum 3).

Create Earth

Cost: 3 per 2 cubic metres to create earth from nothingness (minimum 2); 3 per 4 cubic metres to solidify mud into good earth (minimum 1); round all costs up.

Heat (spell)

Duration: 1 minute. Each minute raises the target’s temperature by 10°. Maximum temperature possible with this spell is 1 500°C (1 800 K).

Cost: 1 for an object up to the size of a fist, 2 for an object up to a cubic metre, and 3 per cubic metre for a larger object. Temperature change can be doubled to 20° per minute for double cost, tripled to 30° per minute for triple cost, and so on. Slower heating costs no less. Same cost to maintain.

Cold (spell)

As for Heat (spell), but temperature is lowered rather than raised.

Resist Cold

Cost: 2 to cast; 1 to maintain. Cost doubles if subject must resist cold of -40°C or lower; cost triples if subject must resist the cold of absolute zero.

Apportation

Cost: 1 for an object up to 500 g in weight; 2 for an object up to 5 kg; 3 for an object up to 20 kg; 4 for an object up to 100 kg; and 4 for each additional 50 kg. Cost to maintain is the same.

Purify Water

Cost: 1 per 4 litres purified.

Time to cast: Usually 1 second per litre, unless a large container and ring are used.

Create Water

Or it may appear as a dense mist of droplets; in this form, four litres of water extinguishes all fires in a one-metre radius.

Cost: 1 per 2 litres created.

Shape Water

A useful shape is a wall of water to stop fiery attacks. 80 litres creates a wall 2 metres high × 1 metre wide. This stops Fireball spells and ordinary fire.

Cost: 1 per 80 litres shaped; same cost to maintain.

Clothing

Complete Wardrobe: 100% cost of living; 10+ kg.

Ordinary Clothes: 20% cost of living; 1 kg.

Winter Clothes: 30% cost of living; 2 kg.

Formal Wear: 40% cost of living; 1 kg.

Cosmetics: 10% cost of living; 1 kg.

Weapon Statistics

Replace all occurrences of “yard” with “metre” (“Reach”, “Range”).

Measure all weights in kilograms by using ½ the quantity of pounds.

Ammunition

For a given gun, the weight of one full load of ammunition, in kilograms, appears after the slash in its “Weight” statistic. Assume that ammo cost is $40 times this weight.

Example: The 5.56mm assault rifle has a weight of “4.5/0.5”. Thus, a full reload weighs 0.5 kg and costs $20.

Armor

Measure all weights in kilograms by using ½ the quantity of pounds.

Shields

Measure all weights in kilograms by using ½ the quantity of pounds.

Miscellaneous Equipment

Replace all occurrences of “yard” with “metre”.

Replace all occurrences of “quart” with “litre”.

Measure all weights in kilograms by using ½ the quantity of pounds.

Camp Stove, Small. Uses 1 litre kerosene per 4 hours.

Cord, 3/16″ = Cord, 5 mm.

Flashlight, Heavy. 10 m beam.

Flashlight, Mini. 5 m beam.

Gasoline. Per litre: $0.50.

Kerosene. Per litre: $0.50.

Lantern. Burns for 24 hours on 500 ml of oil.

Oil. For lantern. Per litre: $4.

Pole, 6′ = Pole, 2 m.

Pole, 10′ = Pole, 3 m.

Rope, 3/8″ = Rope, 10 mm.

Rope, 3/4″ = Rope, 20 mm.

Thermos Bottle. Keeps 500 ml hot or cold.

Water Purification Tablets. Purify 500 ml each.

Wineskin. Holds 4 litres of liquid.

Radio, Backpack. 30 km range.

Radio, Hand. 3 km range.

Radio, Headset. 1.5 km range.

TV Set, Mini. 125 mm × 125 mm flat-screen.

Bug, Audio. 400 m range.

Homing Beacon. Scanner tracks at 1.5 km range.

Crowbar, 3′ = Crowbar, 1 m.

Climbing

Different Gravity

Example: You weigh 70 kg and are carrying 15 kg of gear. On a 1.2-G world, that amounts to an extra weight of (70 + 15) × (1.2 – 1) = 17 kg. Since you’re already carrying 15 kg, your total encumbrance is 32 kg.

Digging

Digging rate depends on the type of soil, the digger’s Basic Lift (that is, ST×ST/10), and the quality of the tools available.

Loose Soil, Sand, etc.: A man can dig BL×50 cubic centimetres per minute (cm³/min).

Ordinary Soil: A man can dig BL×25 cm³/min. One man with a pick can break up to BL×100 cm³/min, making it into loose soil, which is easier to remove. The most efficient way to dig is with one man with a pick, and two shovellers clearing behind him.

Hard Soil, Clay, etc.: Must be broken up first by a pick, at BL×50 cm³/min, and then shovelled at BL×50 cm³/min. A lone man with both pick and shovel can only remove BL×15 cm³/min – he loses time switching between tools.

Hard Rock: Must be broken by a pick at BL×25 cm³/min (or slower, for very hard rock!), and then shovelled at BL×25 cm³/min.

All of the above assumes iron or steel tools! Halve speeds for wooden tools (common at TL5 and below). Divide by 4 (or more) for improvised tools – bare hands, mess kits, etc.

To find the time required to dig a given hole, find the volume of the hole in cubic centimetres by multiplying height × width × depth (all in centimetres, or measure in metres and multiply by 1 000 000 for cm³). Then divide the number of cubic centimetres by the digging rate to find the minutes of work required.

Each hour of work costs 1 FP for loose soil, 2 FP for ordinary soil, 3 FP for hard soil, and 4 FP for hard rock.

Hiking

The distance in kilometres you can march in one day, under ideal conditions, equals 15 × Move.

Jumping

Your Basic Move determines jumping distance, as follows:

High Jump: (15 × Basic Move) – 25 centimetres. For example, a Basic Move of 6 lets you jump 65 cm straight up. For a running jump, add the number of metres you run to Basic Move in this formula. Maximum running high-jump height is twice standing high-jump height.

Broad Jump: (0.6 × Basic Move) – 1 metres. For example, a Basic Move of 6 lets you jump 2.6 metres from a standing start. For a running jump, add the number of metres you run to Basic Move in this formula. Maximum running broad-jump distance is twice standing broad-jump distance.

Lifting and Moving Things

Basic Lift – ST×ST/10 kilograms – governs the weight you can pick up and move.

Throwing

Replace all occurrences of “yard” with “metre”.

Example: You have ST 12, giving a BL of 14 kg. You need to throw a 55 kg body over a two-metre pit. Divide weight by BL: 55/14 = 3.9. This falls between 3.0 and 4.0 in the Weight Ratio column, so treat it as 4.0. The associated distance modifier is 0.15. Multiplying by ST, your range is 0.15 × 12 = 1.8 metres. Oops! The body just hit the bottom of the pit.

Target’s Speed and Range

A distant target is harder to hit. As a rule of thumb, a target up to 2 metres away is close enough that there’s no penalty to hit. At 3 metres, you have -1 to hit; at up to 5 metres, -2; at up to 7 metres, -3; at up to 10 metres, -4; and so on, with each approximately 50% increase in range giving a further -1 to hit.

Consult the Speed/Range column of the Size and Speed/Range Table to find the exact penalty. For ranges that fall between two values on the table, use the larger penalty. For very distant targets, the table provides distances in kilometres.

Example: Infinity Patrol agent Jenny Atkins is shooting on the firing range. The target is 17 metres away. This rounds up to 20 metres, for -6 to hit.

A fast-moving target is also harder to hit. Consult the same column of the table, but use speed in metres per second (3.6 km/h = 1 m/s) instead of range in metres to find the penalty.

If the target is both distant and fast moving, add range (in metres) to speed (in metres per second), and look up the total in the Speed/Range column to find the penalty to hit. (Do not look up the range and speed penalties separately and add them together! Great range mitigates the effects of speed, and vice versa.)

Examples: Agent Atkins fires her pistol at a Centrum spy who is making a getaway on a speeding motorcycle. Her target is 50 metres away and traveling at 96 km/h, or Move 27. This is a speed/range of 50 + 27 = 77. Per the Size and Speed/Range Table, this gives -10 to hit.

Parrying Heavy Weapons

For the purpose of these rules, treat a punch, kick, bite, etc. as a weapon with an effective weight of 1/20 the attacker’s ST. Use half his strength if he made a slam, flying tackle, pounce, or shield rush!

Parrying

Parrying Thrown Weapons: You can parry thrown weapons, but at a penalty: -1 for most thrown weapons, or -2 for small ones such as knives, shuriken, and other weapons that weigh 0.5 kg or less.

Flight Ceiling

On Earth, an unprotected human has trouble breathing past 2 km, and needs an oxygen mask or an advantage such as Doesn’t Breathe past 6 km; see Atmospheric Pressure.

Combat at Different Levels

Change the vertical distance grades to:

• 30 cm of vertical difference, or less
• Up to 70 cm of vertical difference
• Up to 1 metre of vertical difference
• Up to 130 cm of vertical difference
• Up to 170 cm of vertical difference
• Up to 2 metres of vertical difference
• Over 2 metres of vertical difference

Effects of Reach

If your weapon or Size Modifier gives you more than one metre of reach, each metre past the first brings the foe 1 m closer to you. This does not bring you any closer to the foe! For example, a greatsword (two-metre reach) would let you fight as if your foe were one metre closer. If you were standing two metres below him, you would fight as though he were only one metre higher. He would not enjoy a similar benefit unless he, too, has long reach.

Typical Distances

Set distances by common sense and mutual agreement (beforehand, if possible). Some examples: Ordinary stairs rise 20 cm per step. The seat of a chair is 50 cm tall. An ordinary dining table is 80 cm tall. The counter in a shop is about 120 cm tall. The hood of a car, or the bed of a wagon, is about 1 m tall. The roof of a car, or the seat of a wagon, is 130 cm tall.

Dehydration

Replace all occurrences of “quart” with “litre”.

Atmospheric Pressure

We measure air pressure in kilopascals (kPa); air pressure at sea level on Earth is 100 kPa.

Trace (up to 1 kPa): Treat an atmosphere this thin as vacuum (see Vacuum).

Very Thin (up to 50 kPa): The air is too thin to breathe. Earth’s atmosphere becomes “very thin” above 6 km.

Thin (51-80 kPa): Earth’s atmosphere is “thin” between 2 km and 6 km.

Dense (121-150 kPa)

Very Dense (151+ kPa)

Superdense (1 000+ kPa)

These rules assume you are native to 100 kPa and can function normally at 81-120 kPa. If your native pressure differs from 100 kPa, multiply all the pressure ranges above by (your native pressure in kPa/100). For example, if you’re native to 50 kPa, a “dense” atmosphere for you would be 61-75 kPa and a “thin” one would be 26-40 kPa.

Cold

Make a HT or HT-based Survival (Arctic) roll, whichever is better, every 30 minutes in “normal” freezing weather. For most humans, this means temperatures below 2°C, but see Temperature Tolerance. In light wind (15+ km/h), roll every 15 minutes. In strong wind (50+ km/h), roll every 10 minutes. Additionally, strong wind can dramatically reduce the effective temperature (the “wind chill factor”). Also see the modifiers below:

Damage from Collisions

“Velocity” is how fast the character or object is moving in metres per second (3.6 km/h = 1 metre per second).

Collision Angle

Example: A car with 60 HP, moving at 80 km/h (velocity 22) strikes a pedestrian with 10 HP. The pedestrian was fleeing from the car at Move 5, so this is a “rear-end” collision. Collision velocity is 22 (car) – 5 (pedestrian) = 17. The car inflicts (60 × 17)/100 = 10d crushing damage on the pedestrian; the pedestrian inflicts (10 × 17)/100 = 1d crushing damage on the car.

Heat

In ordinary hot weather, you will experience no ill effects if you stay in the shade and don’t move around much. But if you are active in temperatures in the top 5° of your comfort zone or above – over 27°C, for humans without Temperature Tolerance – make a HT or HT-based Survival (Desert) roll, whichever is better, every 30 minutes.

Modifiers: A penalty equal to your encumbrance level (-1 for Light, -2 for Medium, and so on); -1 per extra 5° heat.

In addition, at temperatures up to 15° over your comfort zone (33-47°C for humans), you lose an extra 1 FP whenever you lose FP to exertion or dehydration. At temperatures up to 30° over your comfort zone (48-62°C for humans), this becomes an extra 2 FP.

Intense Heat: Human skin starts to burn at 72°C; see Flame (p. B433) for damage. Even if no damage penetrates your DR, you will rapidly overheat if the ambient temperature is more than 5 × your comfort zone’s width over your comfort zone (e.g., in a fire).

Pressure

Adventurers are most likely to encounter extreme pressure in super-dense atmospheres (see Atmospheric Pressure) or deep underwater (where pressure increases by about 10 kPa per 1 m of depth). Pressures in excess of your native pressure – 100 kPa, for a human – are not always immediately fatal, but present serious risks.

Divers and mountaineers use precise tables to determine decompression times based on time spent at a given pressure. For game purposes, at up to 200 kPa (about 10 m underwater), a human can operate for any amount of time and return without risk. At up to 250 kPa (15 m depth), a human can safely operate for up to 80 minutes and return without requiring slow decompression. Greater pressures reduce the safe time without slow decompression: at 400 kPa (30 m depth), it’s about 22 minutes; at 550+ kPa (45 m depth), there is no safe period.

Radiation

Measure radiation dosage in milligrays, by using 1 rad = 10 mGy.

Vacuum

For example, on the moon – with its month-long “day” – the temperature can range from -152°C (at night) to 107°C (at noon).

Drinking and Intoxication

For simplicity, one drink is a full mug or can of beer (350 ml), a full glass of wine (120-150 ml), or a shot of spirits (50 ml).

Features and Taboo Traits

A race’s native environmental conditions are also features, if they differ from the human norm (humans are adapted to 1G of gravity, have a temperature “comfort zone” of 2°C to 32°C, and breathe 78% nitrogen/21% oxygen at 100 kPa of pressure).

Vehicle Statistics

Move: The first number is Acceleration and the second is Top Speed, in metres/second (multiply by 3.6 to get km/h). These statistics are equivalent to a character’s Move and his top speed with Enhanced Move. For ground vehicles, a * indicates a road-bound vehicle, while a ‡ indicates one that must follow rails. For spacecraft, divide Acceleration by 10 to find it in Earth gravities (G), and note that c means the speed of light (300 000 000 m/s).

LWt: Loaded Weight, in metric tons (1 metric ton = 1 000 kg), with maximum payload and a full load of fuel.

Load: The weight, in metric tons, of occupants and cargo the vehicle can carry, including the operator. To find cargo capacity, subtract the weight of occupants (for simplicity, assume 0.1 metric tons per person, including gear).

Range: The travel distance, in kilometres, before the vehicle runs out of fuel.

Draft: For a watercraft, the minimum depth of water, in metres, it can safely operate in.

Stall: For an aircraft, the minimum speed, in metres/second, it must maintain to take off and stay airborne. “0” means it can hover.

Basic Movement

When adventurers use a vehicle for transportation, it is usually enough to know how fast it can move (Top Speed, in metres/second) and how far it can travel (Range, in kilometres).

Long-Distance Movement

Endurance: Divide Range in kilometres by cruising speed in km/h to determine endurance in hours for situations where “loiter” capability matters more than range. The vehicle must carry provisions in order to take advantage of endurance in excess of one day. Food and water are about 5 kg per person per day, but won’t keep for more than a month before TL5 (at TL5+, canned goods and similar rations are available).

Vehicle Tables

Replace all occurrences of “ton” with “metric ton”.

Measure Top Speed (the second quantity under Move) in metres as m = 0.91 × yards, rounding to whole numbers.

Measure Range in kilometres as km = 1.6 × miles, rounding to whole numbers.

Measure Draft in metres as m = 3.3 × feet.

Ground Travel

Terrain: Figure cruising speed in km/h from Top Speed in m/s as follows:

• Very Bad (deep snow, swamp): Top Speed × 0.2 km/h on wheels or runners, Top Speed × 0.25 km/h on tracks, Top Speed × 0.35 km/h on legs.
• Bad (hills, woods): Top Speed × 0.45 km/h on wheels, Top Speed × 0.9 km/h otherwise.
• Average (dirt road, plains): Top Speed × 0.9 km/h on wheels, Top Speed × 1.8 km/h otherwise.
• Good (paved road, salt flats): Top Speed × 2.2 km/h.

For a road-bound vehicle (e.g. a normal car), use Top Speed only when traveling on a road. Off road, use the lower of Top Speed and 4 × Acceleration in these formulas.

Example: A luxury car with Move 3/52 gets an average travel speed of 52 × 2.2 = 114 km/h on a paved road (Good). On a dirt road (Average), it could manage 52 × 0.9 = 46 km/h. But off road in Average terrain, it would drop to 3 × 4 × 0.9 = 10 km/h!

Water Travel

A powered vessel moves at Top Speed × 3.5 km/h. A sailing craft moves at Top Speed × 3.5 km/h in ideal wind conditions; actual speed can drop to a fraction of this – or even zero – depending on wind direction and strength. A rowed vessel can only sustain a speed of Top Speed × 2.75 km/h (and even this will eventually fatigue the crew).

Air Travel

An aircraft’s cruising speed is about Top Speed × 2.8 km/h. Powered aircraft can reach Top Speed × 3.5 km/h at the cost of burning 50% more fuel, reducing Range. Supersonic aircraft (Move 325+) can only use their full Top Speed at high altitudes where the air is thin (4.5 km and above). At low altitudes, Top Speed rarely exceeds 315-360 (1100-1300 km/h).

Space Travel

It takes about (0.12 × velocity in m/s)/(Acceleration in G) seconds to reach a given cruising velocity. A spacecraft moving at that velocity takes roughly (0.28 × distance in kilometres)/velocity hours to travel a given distance. For comparison, the moon is around 400 000 km from Earth, and Mars is 55 000 000 km away at its closest approach.

Example: To accelerate to a velocity of 80 000 m/s in a spacecraft with an acceleration of 1.5G would take (0.12 × 80 000)/1.5 = 6 400 seconds, or about 1.8 hours. At a velocity of 80 000 m/s, you would reach Mars in (0.28 × 55 000 000)/80 000 = 192.5 hours.

It is common to give interplanetary distances in “astronomical units” (AU). One AU is 150 million kilometres, the average distance from the Earth to the Sun. Interstellar distances are often given in light-years (9.461 thousand million kilometres) or parsecs (3.26 light-years). Earth’s nearest stellar neighbor, Alpha Centauri, is 4.3 light-years away.

To lift into low Earth orbit requires Move 7 800. To achieve planetary escape velocity and leave orbit requires an extra Move 3 300.

Example: A spacecraft in Earth orbit has a delta-v of 200 000. It uses 3 300 to break orbit and 82 000 to accelerate to a cruising velocity (Move 82 000). It drifts at that speed for 1.4 hours to reach the moon, and then use another 81 000 to decelerate to the moon’s orbital velocity. Its remaining delta-v is 200 000 – 3 300 – 82 000 – 81 000 = 33 700.

Some superscience space drives don’t have to worry about delta-v – the spacecraft can accelerate constantly! The only requirement for such a spacecraft to leave a planet is that its acceleration exceeds the planet’s gravity. When it travels long distances, it requires time in hours equal to the square root of (81.75 × distance in millions of kilometres / Acceleration in G) to complete the trip.

Communicators

Standard communicators are radios. They transmit signals by modulating the intensity, frequency, or phase of long-wavelength electromagnetic radiation. This limits them to the speed of light (300 000 km/s); as a result, they are effectively instantaneous for planetary communications but have a noticeable delay over interplanetary distances. Note also that ordinary radio frequencies cannot penetrate more than a few metres of water.

Detailed HP Calculation

Those who have a calculator or spreadsheet program handy may wish to calculate HP instead of using the Object Hit Points Table. HP are equal to 5 × (cube root of weight in kg) for complex, Unliving objects, and 10 × (cube root of weight in kg) for solid, Homogenous ones (round up). The GM may alter these values for unusually frail or tough objects.

Area Maps

The standard scale for these maps is 1:250, where 4 mm = 1 m. Each hex is still one metre across – it is just drawn to a smaller scale.

Room Maps

Draw these maps to any convenient scale. A useful scale is 1:80, where 25 mm = 2 metres (2 hexes) – half the size of a combat map.

Combat Maps

Combat maps are drawn to a scale of 1:40, where 25 mm = 1 metre; each hex is one metre across.

Moving Money Between Worlds

Money in a new world isn’t “legal tender”; it’s a commodity. If you bring medieval gold coins to the 21st century, they will sell as curios – or as gold, for perhaps $1 200 per 100 grams.

Gold and Silver

Historically, gold and silver were very valuable – and many goods were cheap. For an authentic medieval English (14th-century) economy, treat the $ as a “farthing”: a copper coin about 20 mm across. A silver penny is worth $4 and is 10 mm across; 500 such coins ($2 000) weigh one kilogram. If gold and silver trade at 20 to 1 (a reasonable ratio for much of history), a kilogram of gold is worth $40 000! A man could carry a king’s ransom in his backpack.

On the other hand, a GM who wants wealth to be less portable might assume that the $ is a 25-gram silver coin, like a silver dollar. A 25-gram gold piece would then be worth $20. At that rate, 40 coins would weigh one kilogram; a kilogram of gold would be worth only $800. In such a world, precious gems are the only way to carry a large amount of wealth in a small package, and caravans loaded with gold might actually exist!

Parachronic Field Generator

Subquantum Conveyors: Each metric ton of capacity adds $10 million and 5 kg.

Quantum Conveyors: Each metric ton of capacity adds $150 million and 5 kg.

Two-Quantum Conveyors: Each metric ton of capacity adds $300 million and 15 kg.

Power System

A typical pulsed power system for the field generator costs $50 and weighs 2 kg per kJ.

Conveyor Operation

A typical conveyor, after subtracting its own mass, can transport anywhere from 250 to 1000 kg of occupants and cargo.

Parachronic Detectors

The portable unit most often carried by Infinity Patrol agents costs $560 000 and weighs 25 kg; it is the size of a large backpack, and has a 1 km range. Large models are $1 million and 125 kg per kilometre of range.

Active Defense Modifiers

Above attacker: +1 if 1 m difference, +2 if 130 cm, or +3 if 170 cm

Below attacker: -1 if 1 m difference, -2 if 130 cm, or -3 if 170 cm

Size and Speed/Range Table

Note that there is no Speed/Range modifier for a ranged attack at 2 metres or less – shooting a close target is no easier (and no harder) than attacking it in melee combat!

Examples: A man 8 metres away is -4 to hit. A motorcycle rider 40 metres away, traveling at 30 m/s (108 km/h), has a speed/range of 40 + 30 = 70 metres, which gives -9 to hit. A missile passing within 5 metres while moving at 1 km/s has a speed/range of 5 + 1 000 = 1 005 metres, for -17 to hit.

Continue this upward progression indefinitely, with each 10× increase in linear measurement giving +6 to SM or -6 to speed/range modifier.

Example: Erin the archer shoots at a dragon. It is 40 metres away and flying at Move 15 (54 km/h): 40 + 15 = 55 metres. Erin rounds up to 70 metres, for a speed/range modifier of -9. The dragon is 6 metres long, which rounds up to 7 metres, for SM +3. Erin’s final modifier to hit is -6.

By using the sum of range and speed, the table ensures that when one of range or speed is large relative to the other, only that factor has a significant impact on the outcome. Small variations in speed are negligible when firing at targets at extreme ranges, and vice versa. If a rocket is moving at 1 km/s, it doesn’t really matter whether it’s 50 or 100 metres away. If an elephant is 1 km away, it hardly matters whether it is walking at 1 m/s or 2 m/s.

Firing Upward and Downward: For every metre of elevation your target has over you, add one metre to effective range. For every two metres of elevation you have over your target, subtract one metre from effective range; if this would reduce effective range to less than half the real ground distance, use half the ground distance instead.

Object Hit Points Table

Optionally, calculate HP as 5 × (cube root of empty weight in kg) for Unliving objects and 10 × (cube root of empty weight in kg) for Homogenous or Diffuse ones. Round up in both cases.

HP and DR of Structures

HP: The structure’s Hit Points. Optionally, this can be calculated for buildings: HP = 100 × (cube root of building’s empty weight in metric tons), and typical weights per square metre (m²) of area are 0.5 metric tons for wood frame or mud brick, 1 metric ton for steel frame or brick, and 1.5 metric tons for stone.

Cover DR

The following table gives the DR per cm of thickness that common materials afford as cover.

Injury Tolerance

Swarm: Your outer perimeter travels at your best applicable Move; maximum radius is 1 km (buy Area Effect to change this).

Lifting ST

Super-Effort: You can make truly heroic lifts! Your Lifting ST works as usual except when you use extra effort. Then ignore the ordinary extra effort rules. Instead, find your Lifting ST level in the Size column of the Size and Speed/Range Table, read across to the Linear Measurement column, and use the number of metres as your ST bonus for the lift. For instance, Lifting ST +20 gives +5 000 ST.

Penetrating Vision

For instance, Penetrating Vision 1 can look through five 30 mm walls as easily as one 150 mm wall, and these can be any distance apart – but a large total distance would still give a Vision penalty.

Permeation

Finite Thickness: Value depends on thickness: -50% for a thin membrane (like a curtain), -30% for 30 mm, -15% for 200 mm, and -5% for the distance you can sprint in a second.

Precognition

If the GM prefers, he can roll whenever the user has an encounter that might trigger a vision… but at a penalty found by consulting Long-Distance Modifiers and reading “kilometres” as “weeks”.

Snatcher

More Weight: Your weight limit is higher than 2 kg.

Each further +30% multiplies weight by 10 (e.g. a metric ton is +80%).

Super Climbing

The meaning of “+1 Move when climbing” is clear for Clinging, with its climbing speed of half Basic Move. For conventional climbing, though, the table under Climbing doesn’t give Move in metres/second. Assume that each level of Super Climbing raises climbing speed by the base value on the table. For instance, Super Climbing 4 gives +12 rungs/second to climb up a ladder in combat, +24 m/min to climb up a rope out of combat, and so on.

Super Jump

Maneuverable: For instance, if you can jump 100 metres at 20 metres per second, you can “fly” at Move 20 for five seconds before landing.

Lighter Than Air: For each second you’re airborne, your landing zone drifts a metre in the direction the wind is blowing per 10 km/h of wind speed. For instance, if you’re in the air for three seconds in a 30 km/h wind from the west, you’ll land 9 metres east of your intended target.

Telecommunication

Directional Sound: Base range is 100 metres in a direct line of sight.

Gravity-Ripple Comm: Base range is 1 500 km.

Neutrino Comm: Base range is 1 500 km in a straight line.

Sonar Comm: In air, Sonar Comm has a base range of 0.5 metres multiplied by air pressure in kPa.

FTL: Recommended signal speed is 0.1 parsec/day, to a maximum range in parsecs equal to 1/10 000 ordinary range in kilometres, but the GM can adjust this to suit the setting.

Temperature Control

Passive: Spirits, monsters, and elemental creatures of heat and cold sometimes alter the temperature in their immediate vicinity (a two-metre radius) at all times. To simulate this, add Always On (-10%), Emanation (-20%), and either Cold (-50%) or Heat (-50%). The ambient temperature changes by 1° per level per second the entity remains in the area, to the usual maximum of 20° per level.

Add Talent/2 (round down) degrees per second of temperature change after all modifiers, but Talent has no effect on the maximum change.

Walk on Air

Lighter Than Air: Wind moves you a metre per second in the direction it’s blowing per 10 km/h of wind speed.

Maximum Height: A 10-metre limit is -10%; a 3-metre limit is -20%; and a 1.5 m limit is -25%.

Warp

Replace all occurrences of “yard” with “metre”.

Drift: You appear at a random location somewhere in a circle with a radius equal to 1% of the distance you teleported (minimum 1 metre); e.g., if you teleported 10 km, you’d materialize somewhere in a 100 m circle around your target.

Control

Replace all occurrences of “yard” with “metre”.

For solids and liquids, you can affect up to 5 × (level squared) kg of matter in the form of a single object or amorphous mass. For example, Control 3 (Iron) would let you affect a 45 kg iron ingot or even 45 kg of iron filings in a heap… but against a foe with a 1 kg sword, 2 kg helmet, and 9 kg breastplate, all iron, you could only affect one target, even though the total weight is much less than your limit.

Collective: You still can’t affect more than 5 × (level squared) kg of a solid or liquid. For instance, Control 2 (Metal) with Collective lets you affect up to 20 kg of any one metal in a two-metre circle; in the example under Limits of Control, you could affect the sword, helmet, and breatplate.

Natural Phenomena: Area of effect is 0.1 × level kilometres in radius.

For instance, Control 10 (Oceans) could roughen or calm seas in a 1 km radius, for ±3 to die rolls.

Create

Replace all occurrences of “yard” with “metre”.

Replace all occurrences of “ton” with “metric ton”.

• Solids and liquids can weigh up to 5 × (level squared) kg – 5 kg at level 1, 20 kg at level 2, 45 kg at level 3, and so on.
• Radioactive materials work as poisonous ones. Radiation fields use the rules for hazardous energy. Each point of “damage” is 10 mGy (0.01 grays) instead.

Time-Spanning

Your ability works across time. Rolls to use it this way have a penalty for the time gap between you and your target; use Long-Distance Modifiers and substitute “days” for “kilometres”.

Benchmarking Attacks and Defenses

Radiation: The most lethal radiation accidents actually inflict less than 10 mGy/second. Attacks should rarely exceed 1d×10 mGy.

Elemental Attacks

Replace all occurrences of “yard” with “metre”.

Notes: [12] Inflicts milligrays equal to 10 × damage; see Radiation.

Armor

Icy Skin: Each level (maximum five) gives him DR 1 – doubled vs. heat/fire – and +1 on rolls to break free, and adds HT/2 degrees to the “hot” end of his temperature comfort zone.

Insulated Skin: Each level gives DR 5 vs. energy, divides radiation dosage by 10, and adds 2.5×HT degrees to the “hot” end of the user’s comfort zone.

Movement Abilities

Replace all occurrences of “yard” with “metre”.

Create Door: Permeation (Everything; Can Carry Objects, Heavy, +100%; Costs Fatigue, 1 FP, -5%; Finite Thickness, 30 cm, -15%; Requires IQ Roll, -10%; Takes Extra Time 1, -10%; Tunnel, +40%) [160]. Notes: Lets the user create a “door” through a barrier up to 30 cm thick, regardless of composition.

Mental Abilities

Replace all occurrences of “yard” with “metre”.

Tactical Radio: A long-range (300 km) radio capable of encrypted bursts.

Remote Viewing: After an hour of special exercises and meditation, the viewer can displace his vision to any place on the planet! (Increased Range 19 comes to 20 000 km; Earth’s diameter is about 12 800 km.)

Tactical Radar: It can track five targets at once out to 200 km, identify them at 1/10 that range, and give +3 to hit any of them with an aimed attack.

Attacking

Example of Combined Powers

Replace all occurrences of “yard” with “metre”.

Replace all occurrences of “ton” with “metric ton”.

They all have Telekinesis (TK), but even their strongest telekinetic, Singularity, can’t budge the rubble – his TK 40 can only move 1 600 kg at Extra-Heavy encumbrance.

Special Rules for Psionic Powers

Antipsi helmet lining might grant Mind Shield 6 (Limited, Psionic, -50%), and add $1 000 to helmet cost and 0.5 kg to weight.

Copyright © 2006-2007 Ben Finney <ben+gurps@benfinney.id.au> See document source for license and disclaimer of warranty.

Based on GURPS, and used in accordance with Steve Jackson Games Online Policy.

GURPS is a trademark of Steve Jackson Games.