Low and Zero G Combat Rules

The traveller core rulebook doesn’t contain much in the way of rules for Zero and low G combat, since their setting contains artificial gravity technology to make all situations use Earth gravity. But that’s no fun. So here’s some rules I made up for combat in different gravity. These may change as we playtest them if they’re not working great.

Carrying Capacity

Carrying capacity is normally determined by adding your strength and endurance together to get your maximum unencumbered carrying capacity. Carrying more than this but under twice as much imposes a -1DM on all physical activities. Carrying between twice and three times as much imposes a -3DM.

In lower of heavyier gravity this will be modified however. This is done dependent on the strength of the gravity: a place with one third the gravity as Earth, such as Mars, would allow a character to carry three times as much weight as their basic unencumbered load. A place with twice the gravity would enable them to carry half as much. This scales the same way in terms of double and triple loads.

Carrying capacity can’t be increased by more then x4 (eg: a planet with 0.25G). At Zero-G, carrying capacity is at x4.


Lower gravity means that you are less grounded and thus are more susceptible to the effects of recoil. Consult the following very small chart:

Earthlike Gravity: 0.75G+ incurs no additional recoil penalty
Low Gravity: 0.2G to 0.75G adds 1 to all recoil ratings.
Zero and very low gravity: 0G to 0.2G adds 2 to all recoil ratings

Bracing your back against a wall or some sort of solid object negates these extra penalties.


Movement in gravity of 0.1G to 1G functions the same as in regular gravity, although the lower gravity means that a character’s jumping ability is greatly increased. Consult with the GM if you want to take advantage of this.

Zero G movement (or movement at lower than 0.1G) works a bit different and will use the Zero G skill to determine your movement. If you do NOT have some sort of thruster pack to aid in Zero G movement and you are close to a surface of handhold then when you plan to move make a Zero G skill check first. If you succeed at the check then you may move as normal. If you fail the check then your movement is reduced by 1 meter for each point you failed the check by.

If you are free floating and have no handhold or surface to use to propel yourself then you are stuck. You can’t move and have to hope that your momentum will prepare you towards something you can push off of.

If you end your move near a handhold or surface of some sort then it’s assumed you stopped yourself and will remain at that location on your next turn. However, you pay also elect to “push off” from your location into open space. If you plan to do this then you may ADD the positive effect of your zero G check to your movement for that move. You then direct your character in a straight line towards a certain point and move that number of meters. You may not make any more movement actions this turn. On your next turn (and any subsequent turns) you continue to move that number of meters as a free action. You may make no movement actions until you contact a surface (or activate a thruster pack).

Low and Zero G Combat Rules

Traveller Campaign JamesMarshall