Hella is a harsh planet that was colonized by a few dozen humans about 100 years ago. The gravity of Hella is lower than Earth’s, so all of the plants and animals are enormous. The tilt of the planet makes its climate harsh in the summer and the winter, so the human colony migrates every season. As they migrate, they try not to contaminate the environment (who knows what effect humans will have on it?) and they must be careful of the huge carnivores that also migrate.