Actually oxygen concentration limits the size of arthropods. Fossil records of about meter sized arthropods are known from carboniferous period. Oxygen concentration was then significantly higher and primitive breathing mechanism could feed larger individuals. Structural strength of chitin may be restriction at some size level, though. Behemoth sized individuals would not be possible with Earth's life chemistry even in pure oxygen atmosphere.benwillard wrote: ↑Sun Jun 23, 2019 12:22 pm For the questions about gravity, anyway this planet has been terraformed at some point in the past, as it has trees. Big insects are possible on Earth gravity, if they're not in chitin but in some stronger material.
But unrealistic strength is nice and problem free fictive element in the game. Biters look good, in my opinion. They have enough strange features to be alien monsters instead of earth animals in steroids, but have a nice and recongnizable arthropod like structure.