Expanded Space Rules

Area damage causes characters to be pushed back while in zero gravity. Any untethered character who takes area damage is Pushed Off to 5 feet away from the furthest boundary of the area damage and begins floating away from the centermost source of the area damage. If using variant movement in space rules, such as conservation of momentum, the creature's Speed while floating is increased by the distance the creature moved due to the area damage. If the effect that caused area damage would already move the creature, such as a soldier using Shoving Shot, the creature gains a bonus to Speed for purposes of floating while untethered equal to the distance they were moved by the ability.

While in a vacuum or zero gravity , ranged Strikes with bludgeoning, piercing, and slashing weapons double their range and only take a –1 penalty when used to Strike a target beyond the first range increment for each additional range increment beyond the first. If a creature is in a vacuum with zero gravity, ignore all penalties to the creature's ranged attacks and quadruple their weapon's range.

In a vacuum like space, there's no medium for energy transfer through conduction or convection. Cold, fire, and electricity spells or actions with the cold, fire, and electricity traits don't function in a vacuum. Ignore these rules if the spell or action targets an adjacent target, even if it uses a ranged attack roll. This rule can be especially oppressive and should be avoided if the PCs are reliant on these abilities, and you should feel free to exempt specific traits. Magical effects or weapons with magical upgrades bypass this effect—magic breaks normal physics!

Without the upward flow of hot air, fire and cold effects travel differently in space than you'd expect in a terrestrial setting. Cold and fire spells and actions with the cold and fire trait that have an area, burst, cone, or line and don't have a duration have an increased area in this environment. Double the radius of a burst that normally has a radius of at least 10 feet. Cones become a burst with a radius equal to its length and a range of 5 feet (meaning it must be placed adjacent to the caster or originator), and lines follow the same rules but have a burst radius equal to half their length.

Bleeding is especially dangerous in space due to a reduced volume of blood produced in space and spurting from lack of gravity. While in zero gravity, increase the DC of the flat check to see if a creature recovers from persistent bleeding to 17 (or 12 with appropriate help). While in a vacuum without environmental protections, increase the DC to 20 (or 15 with appropriate help).

Creatures become immune to persistent cold and fire damage while in a vacuum.

When a creature Pushes Off a floating creature or object in a zero-gravity environment, they also Push the creature or object, but each of them move at half Speed. If they use Push Off as a free action after a melee Strike that deals bludgeoning damage or a successful Shove, they both move at full Speed instead. A creature Pushed Off this way becomes untethered and can Grab an Edge if they float past something that can stop their movement and lose the untethered condition.

If an untethered creature or object was already moving in one direction and is Pushed Off in the same direction, add Speed to the distance they float at the end of their turns equal to the amount they moved Pushing Off. If the untethered creature was already moving toward a different but not opposite cardinal direction, add Speed equal to half the distance, and if the untethered creature was already moving in the opposite cardinal direction, instead reduce the amount of distance they float by the distance they moved Pushing Off.

If an untethered creature Strikes with a tech weapon that uses ammunition or petrol while floating in zero gravity , they Push Off from the target of the attack 5 feet plus 5 feet for every damage die of the weapon. If using Auto-Fire or Area Fire, they're Pushed Off in the exact opposite direction as the center of the cone or burst. Spells that use Strikes or target all creatures in a cone or line and deal bludgeoning, fire, piercing, or slashing damage causes an untethered spellcaster to Push Off 5 feet for every damage die of the spell.

Using this rule, all characters move 20 feet instead of their Speed each round while floating untethered. To add verisimilitude, limit which feats, spells, and conditions increase or decrease a creature's Speed while calculating how far you float while untethered, as those that affect your base land Speed wouldn't necessarily make a creature float faster in space.