The Ancient Gods, Part One

The Ancient Gods, Part One is the first single-player expansion for Doom Eternal, and was previously available as a pre-order item to purchasers of the Year One Pass. While some details appeared on the Steam store page for the season pass previously, the expansion was officially announced by Bethesda during the QuakeCon at Home stream on Twitch on, with release of a teaser trailer. A full reveal was then scheduled to follow during the GamesCom Opening Night Live event on August 27. As of the full reveal, it is scheduled for release on October 20, 2020.

Story
Following the Doom Slayer's defeat of the Khan Maykr and the Icon of Sin and the salvation of Earth, the Slayer learns that Urdak has since been overrun by the forces of Hell. To return to Urdak and save the fallen paradise, the Slayer must join forces with the Seraphim, who informs him that it is time for him to "serve the gods yet again".

The Father, now fully restored, recognizes that the Slayer has returned to restore order to Urdak and end what he refers to as a "threat to all of (his) creations."

New enemies
Some new enemies have appeared in promotional materials for the expansion, but few details are currently available:
 * The blood angel, a corrupted Maykr angel wearing red armor and possessing demonic horns, able to fly and attack with its staff. It can charge up its energy in a cruciform display, enabling strong armor which protects its otherwise vulnerable head. Unlike normal Maykr angels, their faces are exposed.
 * The spirit, a ghostly variant of the summoner from Doom (2016). It can possess other demons, preventing their weak points (if any) from being broken and protecting them from faltering; possessed demons also gain significant resistance to damage from the ballista. To defeat the spirit, the host must be killed and then the spirit itself must be eliminated via use of the plasma rifle's microwave beam mod before it can find a new host.
 * Turrets similar to the eyes of Kalibas and those previously found near the top of the Nekravol.
 * An unknown gigantic demon roughly the size of the Icon of Sin, but with differently shaped horns and a missing eye. It may be a Titan. It is not seen fighting the Slayer in the trailer but rather helps him reach a new area, so it may not actually be an enemy. Alternately, it might not be fought when it first appears. Its name was revealed to be Maligog.
 * An unknown demon, presumably a boss, that seems to be a demonic version of the Khan Maykr.

Levels
Official names of the levels are not yet known, but at least the following areas are confirmed to occur:
 * UAC Oceanic Research Base
 * Blood Swamp
 * Equestrian Hold
 * Ruined Urdak