Demons Roots: Yakusoku Sareta Haiboku

After the Demon Lord's defeat, the remaining demons fled to the Dark Realm. A thousand years later, on the verge of extinction, demonkind decides to invade the human world again in one final struggle for survival. However, the world they return to after years in the darkness isn't the same as it once was.

Humans have turned against their fellow man. Downtrodden and defeated, the poor find an unlikely ally: the same demons who terrorized humanity a thousand years ago. Together with the demons, they fight against the world's victors, the ones who hold all the power, to gain their freedom and create a world they can call home.

(Source: Steam)