Whats the goal off the assassins? Just to kill?
Also:
Fire? Can the people somehow make fire or do they have to eat raw stuff?
There should be more plants I think because I mean... all energy comes first from the plants. If there are only certain areas with vegetation, all the herbivores will stick around the plants and so all the carnivores would as well. Is organic trash also dumped on the planet? Because then small forest-like things could have formed, as plants die and decompose into soil where new plants grow or something. Plants are the foundations of all ecosystems so they shouldn't be THAT rare if more advanced races can just go out hunting for food and survive.