Doom 3: Resurrection of Evil

Doom 3: Resurrection of Evil aka RoE is an expansion pack for Doom 3 released April 4, 2005. The PC version was sold as an expansion pack, requiring Doom 3 to install. The Xbox version was sold as a stand-alone game, with Ultimate Doom, Doom II, and the Doom II Master Levels as bonuses on the disc.

The expansion pack included several new monsters, as well as two new weapons.

Plot
Two years after the incident on Mars, research has resumed, led by Dr. Elizabeth McNeil. Once more, strange occurrences haunt the facility. A search team breaks into a chamber deep within Mars, finding the Artifact — a weapon from Hell that the Ancients sealed away long ago.

The lead Marine, upon touching the Artifact, awakens it, the blast wave killing his team and reaching into Hell, alerting the Maledict (Dr. Betruger’s new form). The Maledict sends the three Hunters to retrieve the Artifact. Meanwhile, Hell begins to invade Mars once again.

Weapons
All of the Doom 3 weapons, except the Soul Cube and the chainsaw, plus the following:


 * Double-barreled shotgun
 * Grabber Gun
 * The Artifact

New Monsters

 * Bio-Suit Zombie
 * Bruiser
 * Maledict
 * Vulgar
 * Forgotten One
 * Hell Hunter

Monsters also in Doom 3

 * Zombie
 * Z-Sec
 * Commando
 * Imp
 * Maggot
 * Demon
 * Trite
 * Tick
 * Cherub
 * Cacodemon
 * Hell Knight
 * Mancubus
 * Revenant
 * Wraith
 * Arch Vile

Final Storyline
Upon defeating the Hunters and gaining their abilities, the Marine shuts down four core systems of Mars to power the old teleporters, sending the marine to Phobos and Delta Labs, then finally into Hell. Battling his way through, the Marine eventually reaches the Maledict. After a fierce battle, the cutscene shows the Marine fire a rocket at the Maledict, only to miss and end up in the Maledict's jaws.

Betruger's head pops out and demands the Artifact. The Marine obliges by shoving the Artifact down Betruger's throat, instantly killing the Maledict and destroying the Artifact, leaving only Betruger's skull behind. The screen fades to white, and Dr. McNeil's voice can be heard saying, “Marine...Marine...Welcome home...”, possibly implying that the Marine was sent back to Mars or Earth. It has also been speculated that Dr. McNeil died and simply went to heaven because there was no portal back to Mars.

Spoilers end here.

Levels

 * 1) Erebus - Level 1: Main Excavation
 * 2) Erebus - Level 2: Erebus Dig Site
 * 3) Erebus - Level 3: Erebus Labs
 * 4) Erebus - Level 4: Erebus Control
 * 5) Erebus - Level 5: Erebus Research
 * 6) Erebus - Level 6: Erebus Station
 * 7) Phobos Labs - Sector 1: Teleportation
 * 8) Phobos Labs - Sector 2: Molecular Research
 * 9) Phobos Labs - Sector 3: Main Reactor
 * 10) Phobos Labs - Revisited: Teleportation
 * 11) Delta Labs - Unknown: Union Aerospace Research Division
 * 12) Hell