Doom 3: Resurrection of Evil
Doom 3: Resurrection of Evil
Released n/a
Set in 2147, two years after the events of Doom 3, the UAC detects a strange signal from one of its Martian satellites, and consequently sends a team in to investigate. Finding the Hellstone in the process, the forces of Hell attempt to retake the object from the player, a marine combat engineer who is working for Dr. Elizabeth McNeil. McNeil, an unseen character in Doom 3, was the whistleblower who notified counselor Elliot Swann and Jack Campbell of Malcolm Betruger's mysterious activities at the beginning of Doom 3.
After fighting his way through the complex, the marine eventually meets up with McNeil in the Phobos Labs. She tells him that the only way to destroy the Hellstone is to return it to where it came from: Hell. The marine powers down the base to re-route power to one of the teleporters to reach the Delta Labs, where the main teleporter to Hell is located.
The marine arrives in Hell and battles his way to Betruger, who has become the Maledict. After some fighting, Betruger bites the marine, but before he can eat him, the marine shoves the Hellstone down Betruger's throat, killing him. The game ends with a bright white light, followed by McNeil's voice saying, "Welcome home, Marine."

Little is known about the history of the Hellstone. While the Soul Cube from Doom 3 was created by an ancient Martian civilization to defeat Hell, the Hellstone is a Hell-created object which offers the user a wide array of powers.
Both of these artifacts are powered by living souls. However, the Soul Cube uses souls that were willingly sacrificed to power it, while the Hellstone seems to pull unwilling souls into it. If careful attention is paid when the Hellstone is capturing a soul, one can see that the soul in question is clearly in anguish over the procedure.
The Hellstone seems to have been a loophole created by the forces of Hell as a way of bypassing the barrier created by the Soul Cube during the events of Doom 3. By touching the Hellstone, the forces of Hell had another way to invade the mortal realm.

Using the Hellstone is akin to using the Soul Cube. Floating inches from the user's hands, it beats regularly.
While the Hellstone was obviously designed to aid the forces of Hell, demons are not immune to the weapon's powers. The wielder acquires the powers of slowing down time, enhanced damage, and temporary invulnerability from the demons created to retrieve the Hellstone.
A user who activates the Hellstone cannot choose between the powers of slowing down time, enhanced damage, and temporary invulnerability. All available powers are activated at the same time.
To retrieve the abilities for the Hellstone, the player must defeat the three Hell Hunters (bosses): Helltime Hunter, Berserk Hunter, and Invulnerability Hunter.