evolution system

It was the six hundredth year since humans started to leave Earth to colonize other planets. Gradual was one of the planets they had colonized and during the most time they were there, they believed they were alone. But in the fourth year of human existence on Gradual, they were attacked by raven beasts, winged creatures born by the planet itself. Immune to all energy weapons of humans. The fight with the raven beasts cost humanity over a billion lives before they finally got victory. Such an expensive victory made the humans bitter, and they directed their wrath to one of the civilizations they had signed a peace treaty with, the AIs, the planet was shared by humans and Gradual but when the war came, the Graduals stayed out of it. Humans protested at all AI bases in Gradual but the AIs remained silent about the whole issue and over time their relationship began to show strains.