From the introduction:
Compatible with FIST kind of.
...
PLANET FIST is a total conversion hack of FIST: Freelance Infantry Strike Team Ultra Edition
...
PLANET FIST is set on the planet Sixaura, a faraway world cut off from the rest of the galaxy by a destroyed jump gate, now ruled by three empires: the corporate libertarian New Committee, the orthodox fascist Tyrat Council, and the techno-supremacist Velian Ascendancy. These ruling bodies fight an unending—in truth, unwinnable—war for control of their new forever-home. This endless march of murder and death is sustained by nanotechnology, a scientific breakthrough first made on Sixaura. Sixauran Scientists perfected the art of replicating known substances with programmable “nanos,” and continued their research until their machines crossed the final barrier: flesh itself.