When the Bioscientists came to Mars, the planet was dead, but they tried to create new creatures that could live in any environment. They succeeded, and soon Mars was full of aggressive, durable monsters. They used fossils found on Mars to design these creatures.
Some of these monsters were really dangerous, such as the Mothecysar and the Urgot, which eat people for food. People can’t kill these creatures with guns. The only way to kill them is to stab them in the head with a sword, but that is very dangerous, so few people were willing to do it…
But the monsters were so aggressive that the Bioscientists had to hide underground in bunkers. They asked the Mechanics and the Physicists for help... but those other groups refused, so the Bioscientists had to fight alone.
They trained an army of warriors to fight the Mothecysar and the Urgot, but their battle was going badly.
Here is picture of a Mothecysar and an Urgot fighting:
Sometimes when they are hungry, the Mothecysar and the Urgot fight one another for food. But they prefer to hunt humans because it's hard to beat each other in a fight, and humans are much easier pickings.
Just before the Great War, the Urgot and Mothecysar are fighting each other often because the Bioscientists have run out of supplies and are hiding, while they prepare to surrender to one of the enemy groups and escape Mars.