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Simplifying Gravity

I have copious notes for a hypothetical GURPS Fourth Edition space patrol game I may or may not run some day. Here is how I would simplify the effects of gravity and space sickness.

Note: I reference the G-Experience advantage below. In this campaign, G-Experience comes in only 2 levels. For 5 points, you have experience with a single gravity band as defined below. For 10 points, you have experience with all gravity bands.


To simplify the effects of gravity, use the following gravity bands. The exact G values of each band are unimportant; the listed penalties and effects are average for the band.

Very Heavy: Very heavy gravity affects coordination, giving -5 to DX for activities that require agility or judgement of ballistic trajectories, such as Broadsword, Driving, or Guns, but not Beam Weapons or Lockpicking. The heart has to work harder to pump blood to the brain, resulting in -2 to IQ, HT, and FP. Multiply the weight of all gear by 2 and add 100% of body weight for purposes of encumbrance. Divide jumping and throwing distances by 2.

Heavy: Heavy gravity affects coordination and circulation, though less than very high gravity, giving -3 to DX and -1 to IQ, HT, and FP. Multiply the weight of all gear by 1.5 and add 50% of body weight for purposes of encumbrance. Divide jumping and throwing distances by 1.5.

Normal: Gravity is within a normal human's tolerances. No effect on the character.

Light: Light gravity is disorienting like heavy gravity, giving -2 to DX. There is no effect on the heart, however, so no penalty to IQ, HT, or FP. Divide the weight of all gear by 2 for the purposes of encumbrance. Multiply jumping and throwing distances by 2.

Very Light: Disorientation is greater, increasing the DX penalty to -3. Divide the weight of all gear by 4 for the purposes of encumbrance. Multiply jumping and throwing distances by 4.

Microgravity: Disorientation gives -4 to DX. Divide the weight of all gear by 10 for the purposes of encumbrance. Multiply jumping and throwing distances by 10. Microgravity may cause space sickness.

Zero-Gravity: Disorientation gives -4 to DX. Skills and DX rolls are limited by Free Fall skill (see p. 00). The weight of your gear is effectively 0 for the purposes of encumbrance. You can only move by pushing off solid surfaces; Move when doing so is equal to ST/2, rounded down. Zero-gravity may cause space sickness.

Certain advantages alter the way gravity affects the character. If you have G-Experience for the local gravity band, halve the associated DX penalty. Improved G-Tolerance reduces all penalties. At the 5-point level, multiply all penalties for local gravity by 2/3. At the 10-point level, multiply all penalties by 2/5. These effects are cumulative; round all penalties down at the end. The Gravity Adaptation perk lets you ignore the DX penalty for one band with a single DX-based skill.

Native Gravity

If your species evolved in a gravity band other than Normal, you must renormalize the bands to your native gravity. Treat your native gravity band as Normal, and increase or decrease the attribute penalties of other bands relative to your native band, to a maximum of Very Heavy and a minimum of Microgravity. Do not change the effects on encumbrance or jumping and throwing distances.

For example, if you come from a world with Heavy gravity, you suffer no penalties on Heavy worlds. You treat Very Heavy gravity as if it were Heavy, Normal as Light, Light as Very Light, and Very Light as Microgravity.

Space Sickness

Those who are not native to micro- or zero gravity (“free fall”) may become nauseated and disoriented by the constant falling sensation. Roll against the higher of HT or Free Fall when you first enter free fall. The Space Sickness disadvantage gives -4.

On a success, you are unaffected. On a failure, you are nauseated (see Afflictions, p. B428), which may trigger vomiting. If you begin to retch while wearing a vacc suit, you may choke; treat this as drowning (see p. B354). Roll against the better of HT or Free Fall every 8 hours to recover. If you suffer from Space Sickness, you cannot adapt!

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