The world we live in is dream of the ultimate God - Svarog. He is resting happy, because he made such a wonderful creation - The Earth, and the Humans. He put his two sons - Perun and Chernobog, to protect the Humans from the evil forces from The Underground.
One day, Chernobog fell almighty, and started to torture people, and make them evil. He united with the Underground, forming the army whose ultimate goal is to wake up Svarog, thus making the Apocalypse, pushing this world to the oblivion.
Your sister was kidnapped by the evil forces of Chernobog. Your goal is to skirmish them, beat Chernobog, find your sister, and ultimately protect Svarog from his awakening, thus saving this beautiful world from The Apocalypse.