Map 01 - Compound: You are working as an engineer for a major company. Suddenly the base goes silent. You pull out your handy pistol and attempt to blast your way out of the compound.
Map 02 - Haunted Mines: As you are leaving the compound via water tunnel you recieve a faint transmission from a mining company that is near the exit of the water tunnel. They found a demon artifact while digging. The artifact flooded the mines with poison. All of the workers down in the mines died and their souls were sucked into the artifact. Moving the artifact may trigger it to unleash it's captured souls.
Map 03 - Helliseum: The artifact the miners found may have a direct relation to the hell that Earth has been facing. You fall into a pit that is a direct entrance to Hell. More specifically the arena in Hell. Yes, there is an arena in Hell. And now your only hope to escape is to fight for Satan's entertainment.
Map 04 - Slathe: You find out who is behind the invasion on Earth. Not the artifact. Not Satan (Even though he is very impressed.) No, none of them. The invasion on Earth was caused by me. Yes, that's right me. I was bored and I had absolutely nothing better to do than to reach my arm into the sky and punch the face of God.