Advanced Environmental Conditions

Variable Gravity Conditions

Zero Gravity

Movement in zero-g is not the same as flight. Controlled movement is difficult without some form of propulsion, and creatures without something to push off from often find themselves floating aimlessly. If a creature is adjacent to or in the same square as an object (including a wall, floor, or ceiling) or another creature one size category smaller than itself or larger, it can expend an amount of its movement to push off that object or creature, moving at half the expended speed in a direction of its choosing (as appropriate); if that object or creature is movable, it begins moving in the opposite direction at that same speed.

Movement in zero-g is limited to straight lines; a creature can only change course by pushing away from larger objects such as bulkheads. If a creature runs into a solid object durings its movement, it must succeed at a DC 13 Acrobatics or Athletics check to stop its movement; failure means the creature has disadvantage on its next ability check or attack roll. Creatures that ignore difficult terrain may ignore this check. Creatures wearing an Enviro-Suit may move normally along a stable surface such as a bulkhead or asteroid surface.

A creature that moves in a given direction continues to move in that direction at the same speed at the beginning of its turn each round without expending its movement speed; it must move the full distance unless it is able to change its motion by latching on to an object or creature, pushing off in a new direction expending movement speed at least equal to its current momentum, or creating thrust of some kind.

If provided with sufficient handholds, a creature with a climb speed can move along a wall at full speed, as can any creature that succeeds at a DC 13 Acrobatics or Athletics check (on failure, move at half speed). Creatures that ignore difficult terrain may ignore this check and move at full speed. Creatures that fly via methods that require an atmosphere, such as wings, can’t use their fly speeds in a vacuum. Methods of flight that provide their own thrust, such as jetpacks and rocket boots, are not affected, nor is flight speed granted by Force powers, Tech powers, or class features.

A creature's normal carrying capacity increases by 10 times in a zero-gravity environment. In addition, the creature gains a +20 bonus on any Strength check made to lift or move a heavy unsecured object.

Thrown weapons have their range increments multiplied by 5 in zero-g. Blasters’ long range increments are unlimited in zero-g, but disadvantage on long range attacks still applies.

Long-term exposure to zero gravity conditions can cause serious problems when returning to normal gravity. A creature that spends 120 hours or more in a low-gravity environment temporarily reduces their Strength score by 1d6 upon returning to normal gravity. This reduction is resolved in 1d6 days of acclamation to normal gravity.

Low Gravity

Low-gravity worlds are liberating to most species acclimated to standard-gravity worlds. Such characters’ muscles are far more effective than normal. On a low-gravity world, where the gravity is no greater than a third of standard gravity, creatures can jump three times as high and as far and lift three times as much. (Movement speed, however, stays the same, as moving in great bounds is awkward and difficult to control.)

A creature's normal carrying capacity is doubled in a low-gravity environment. In addition, the creature gains a +10 bonus on any Strength check made to lift or move a heavy unsecured object. Creatures attempting to climb or swim have advantage on related ability checks. Falling damage is reduced from 1d6 points per 10 feet fallen to 1d4 points per 10 feet fallen.

Thrown weapons have their range categories tripled. Blasters’ long range increments are tripled in low gravity, but disadvantage on long range attacks still applies.

Long-term exposure to low-gravity conditions can cause serious problems when returning to normal gravity. A creature that spends 120 hours or more in a low-gravity environment temporarily reduces their Strength score by 1d6 upon returning to normal gravity. This reduction is resolved in 1d4 days of acclamation to normal gravity.

High Gravity

On high-gravity worlds, creatures are burdened by their increased weight, and their physical abilities are affected accordingly. On a high-gravity world, where the gravity is at least twice as strong as standard gravity, a creature and anything it carries weighs twice as much as on a standard-gravity world, but the creature has the same amount of strength. Creatures unaccustomed to high gravity environments move at half their movement speed, and can jump only half as high or as far.

A creature's normal carrying capacity is halved in a high-gravity environment. In addition, the creature takes a -10 penalty on any Strength check made to lift or move a heavy unsecured object. Creatures attempting to climb or swim have disadvantage on related ability checks. Falling damage is increased from 1d6 points per 10 feet fallen to 1d8 points per 10 feet fallen.

Thrown weapons (though not those of natives) have their ranges cut in half as they fall to the ground more rapidly.

Long-term exposure to high-gravity conditions can cause serious problems when returning to normal gravity. A creature that spends 120 hours or more in a high-gravity environment temporarily reduces their Dexterity score by 1d6 upon returning to normal gravity. This reduction is resolved in 1d4 days of acclamation to normal gravity.

Extreme Gravity

A planet where the gravity is at least five times as strong as standard gravity is extremely dangerous to most creatures. In addition to the limitations of high gravity (see above), a creature in this environment takes 1d6 kinetic damage per round.

Variable Atmospheres

A normal atmosphere is one that can support the majority of breathing life-forms. Most such atmospheres are composed of some combination of oxygen, nitrogen, and other nontoxic gases. However, many plaents and environments have atmosphere that are less supportive of humanoid life.

Thick Atmospheres

A nonacclimated creature operating in a thick atmosphere treats it as somewhat harmful, due to the extra chemical compounds in the air and the increased atmospheric pressure. Every hour, such a creature must succeed at a Constitution save (DC = 10 + 1 per previous check) or become poisoned. This condition ends when the creature returns to a normal atmosphere. Conversely, the increased weight of the air grants a +5 bonus to existing flight speeds and a +5 bonus to Pilot checks to keep an aircraft in flight.

Severely thick atmospheres are far more dangerous. Every minute, a creature in such an atmosphere must succeed at a Fortitude save (DC = 10 + 1 per previous check) or begin to suffocate as its lungs cease coping with the density of the oxygen inhaled and lose the strength to keep pumping air into its bloodstream.

Thin Atmospheres

Thinner atmospheres tend to cause a nonacclimated creature to have difficulty breathing and become extremely tired. A typical thin atmosphere requires such a creature to succeed at a Constitution save each hour (DC = 10 + 1 per previous check) or become weakened. The weakened condition ends when the creature returns to a normal atmosphere.

Severely thin atmospheres can cause long-term oxygen deprivation to those affected in addition to the effects of a standard thin atmosphere. The first time a creature in a severely thin atmosphere fails its Constitution save, it must succeed at a DC 20 Constitution save or reduce all ability scores by 1. This reduction is resolved in 1d4 days of acclamation to normal atmosphere. A creature acclimated to high altitude gains a +5 bonus to its saving throw to resist this effect.

Toxic Atmospheres

Toxic atmospheres are composed of poisonous compounds and vary radically in their consistencies. Some toxic atmospheres are capable of sustaining oxygen-breathing life-forms, while others immediately suffocate those within them. Regardless of whether or not they allow creatures to breathe, toxic atmospheres are threats to most living creatures, as they act as an inhaled poison. Though the specific type of poison varies, many toxic atmospheres act as existing poisons but with radically different onset times and save DCs. Low-level toxic atmospheres can have onset times measured in hours or days, while heavily toxic atmospheres have onset times measured in rounds.

Severe & Fatal Temperatures

The Extreme Heat & Cold rules provided in the Dungeon Master's Guide suffice for weather conditions on most terrestrial planets. However, some worlds have temperatures more acute and threatening to beings who dare to visit them. The following rules deal with temperatures beyond the Extreme Heat & Cold rules.

Severe Heat

In severe heat (above 120° F), a creature must attempt a Constituion saving throw once every 10 minutes (DC = 10 + 1 per previous check) or gain a level of exhaustion. Characters wearing heavy clothing or armor of any sort take a –4 penalty to their saves. A character can attempt a Survival check to receive a bonus to this saving throw and might be able to apply this bonus to other characters as well.

Creatures wearing medium or heavy armor, or who are clad in heavy clothing, automatically fail the saving throw. Creatures with resistance or immunity to fire damage have advantage on the saving throw, as do creatures adapted to hot climates.

Fatal Heat

In fatal heat (air temperature over 140° F, boiling water, fire, and lava) deals fire damage. Breathing air in fatal heat deals 1d6 fire damage per minute (no saving throw). In addition, a character must attempt a Constitution saving throw every 5 minutes (DC = 10 + 1 per previous check) or take 1d4 fire damage. Hotter environments can deal more damage at the GM’s discretion.

Severe Cold

In conditions of severe cold (below -25° F), an unprotected creature must succeed at a Constitution save every 10 minutes (DC = 10 + 1 per previous check) or one level of exhaustion. Creatures with resistance or immunity to cold damage have advantage on the saving throw, as do creatures adapted to cold climates.

A character can attempt Survival skill checks to gain a bonus to this saving throw and might be able to apply this bonus to other characters as well.

Fatal Cold

Conditions of fatal cold (below –50° F) deals a creature 1d6 cold damage per minute (no saving throw). In addition, a creature must succeed at a Constitution save (DC = 10 + 1 per previous check) each minute or take an additional 1d4 cold damage. Colder environments can deal more damage at the GM’s discretion.

Survival Items