Movement in Space

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.