Doom 2: Hell On Earth Info

Realizing that closing the portal from Earth's side isn't enough, the Marine steps through the gateway into Hell itself to destroy the invasion at its source. Ending Text: The Victory

Once the ships have safely launched, the Marine is the last human left on Earth. He discovers that the source of the invasion is a massive interdimensional portal located in his own hometown. Doom 2: Hell On Earth

If you are looking to purchase a copy of the game or its related media: Realizing that closing the portal from Earth's side