There is a Legacy version here.

Subjective Gravity

Source GM Core pg. 172
All bodies of mass can be centers of gravity with the same force, but only if a non-mindless creature wills it. Unattended items, objects, and mindless creatures treat the plane as having microgravity. Creatures on a plane with subjective gravity can move normally along a solid surface by imagining “down” near their feet. Designating this downward direction is a free action that has the concentration trait. If suspended in midair, a creature can replicate flight by choosing a “down” direction and falling in that direction, moving up to their Speed or fly Speed. This pseudo-flight uses the Fly action.