A setting specific science fiction variant of Searchers of the Unknown. From the intro:
Human colonists from a distant star discovered a large planet covered in dense nutrient-rich fluid with a thick exotic atmosphere and attempted to terra-form it using machinery lowered into the dense jungle. Genetic research led to the creation of humanoids whose bodies leeched off the nutrients in the exotic atmosphere and waters to feed, heal and breathe. These altered humans were called Symbi (from ‘symbiotes’).
Centuries after the colonists departed to wage war in a distant galaxy, the Symbi remain, awaiting the ‘Gods’ return.
The terra-forming resulted in the atmosphere being less dense in places, which has had the effect of stunting the flora and fauna in these areas, now marshland where the nutrient waters rise to knee-height. Further beyond the terra-formed areas are swamps, where the waters are ankle-height. Areas beyond the swamps are covered in dense Jungles, where the waters lie beneath a woven ‘crust’ of seaweed. This is the closest the PCs will get to walking on dry land. Each day the party travels the Referee should roll on Table 1 to ascertain what the environment is. The ancient terra-forming machines often hibernate during self-repair, causing the atmosphere and surface to rapidly revert to swamp or even Jungle overnight.