Prologue-

Marine leaves Mars on a shuttle home after events of Doom3, end of Doom3 is shown in some form to educate people who haven't played it.

A link is established within the Marines shuttle. Contact is from Earth via transmission and is given a debriefing on news from Earth of a possible attack to something possibly similar to events on Mars via a military general. Reports indicate that a portal is emerging within Cairo city. "Unknown extra terrestrials" are emerging from within and invading the city itself in small numbers.

Part 1-

Marine instructed to land shuttle at moon base to meet with special force tasked with combatting the invasion. Marine is to be equipped with gear to fight the invasion due to his experience and expertise.

Upon leaving in a new shuttle which is equipped for military invasive use, the shuttle enters Earths orbit, various other shuttles accompanying the marines ship from the moon base are taken down and destroyed by airborne demonic swarms. Marine witnesses this from his own personal shuttle. Some onboard with the marine are panicking, others are excited.

Marine's shuttle is struck by a large force and any view of the outside is hindered by the swarm that attacks the other craft. Power goes out inside the shuttle, and all is dark, troops on board are advised to switch on night vision, the pilot of the shuttle is possessed and leaves his seat and leaps back into the passenger section of the ship and tries to attack military members on board the shuttle and is killed by one of the military members, and while the lights are going on and off, demonic whispering and screaming is heard. The shuttle goes down into a valley. Some members of the force accompanying the marine in the same shuttle have survived and are told to regroup and meet on the crest of a mountain to evaluate the situation and to plan an attack.

Part 2-

Mass panic and radio pvssyr ensues as more military shuttles are destroyed whilst on course to land, and reports of military bases are being overrun by monsters 'never seen before'. The invasion is ramping up, and more invading creatures are entering the fray in the hundreds. Large military ships are seen floating in the sky attacking the airborne swarms, and bombarding those on the ground, echos of artillery shots, conventional weapons, and plasma weaponry are heard. A war is happening. Marine assumes these invading forces must be what he encountered whilst on Mars.

Military forces are told over radio transmission that it is too dangerous and to abort and retreat by a commanding officer of the military handling the situation. As the Marine rises over the crest to evaluate the situation with some other members of the military, the varse expanse of Cairo city is revealed, amongst the airborne battles and chaos below it is a beautiful sight. Until shorly after a nuclear bomb is dropped far in the distance in an effort to annihilate the invasion. The mushroom cloud is enormous, and all surviving military personnel heard panicing over radio pvssyr suddenly ends abruptly. All is quiet. Everyone flees to cover, and those who couldn't quite make it are killed, and the Marine is knocked out from debris.

Marine is woken by a survivor, and raised to his feet. The Marine is informed that "Things are looking real grim.. there is no contact from any of his squad, or even the military itself. Everything has gone dark". The survivor then quotes "It's like Hell on Earth"

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