Fortress of Doom

The Fortress of Doom is a space station used by the Doom Slayer as his personal headquarters. It was designed by the people of Argent D'Nur but built around a core of Maykr technology, originally intended as a base of operations for the Night Sentinels: it is implied to be one of many such structures, though the fate of the others is unknown. VEGA describes it as a "flag-station," implying it is a particularly large or well-equipped example of a Sentinel warship.

The Fortress is initially operated by the backup copy of the AI VEGA that the Slayer made before overloading VEGA's original core. Later this is switched for the consciousness of Samuel Hayden after the Slayer disconnects VEGA but still requires control of the station.

The Khan Maykr still retains some degree of control over the station's systems and attempts to trap the Doom Slayer by shutting off its power, but had not planned on the Slayer being able to use the Crucible he recovered during the events on Mars as an auxiliary power supply.

The Fortress is not technically a spaceship as has no conventional engines: instead it uses an unknown form of space-folding technology based on Sentinel Energy to reposition itself while remaining stationary.

Layout
The upper level of the Fortress consists of the bridge at the front of the station, with computer consoles and a main viewscreen. Aft of this are a couple of terminals one of which creates the Freeze Bomb item, and two interface terminals which are later used to hold the remains of Samuel Hayden, and the first Crucible.

The second deck down contains the Slayer's personal quarters, a fabrication machine that creates the Ballista, and a number of locked chambers at the rear of the station containing useful items. Directly forward of these chambers is a locked cage containing the Unmakyr, requiring six Empyrean Keys to open. Exits to the sides provide access to the two side-towers, though one has a partially destroyed access walkway.

The lower level includes side-chambers with more items, a destroyed Atlan mech torso in some kind of service gantry, and an elevator to the bowels of the ship where the Slayer maintains a demon prison as a training area, dubbed the "Ripatorium."

Easter Eggs
The Slayer's personal quarters, located at the front of she ship on the second deck down, are filled with Easter eggs, mostly references to games by Id or Bethesda, or those with some relation to the Doom series.


 * Flynn Taggart is referenced three times: a log-in credential in the computer that unlocks Doom 2, a biography/story book about him titled Ret-Conned: The Life and Times of Flynn Taggart, and a company that bears his family name, Taggart Comics Group. There is also a couple of books written by Jill Lovelace, the other character from Doom novels, Knee-Deep In The Dead and Hell on Earth. Both of these books also refer to the novels based on the original Doom dilogy.
 * Commander Keen's skull on the bookshelf, which is also portrayed on one of the collectible vinyls.
 * A Soul Cube from Doom 3 is found on the Slayer's main computer desk.
 * Copies of the previous Doom games and other games developed by id Software, such as the Wolfenstein and Quake series.
 * Wolfenstein and Quake games are also referenced by various books and vinyls.
 * A book about Dopefish.
 * A book titled "My Buddy Superfly" by H. Miyamoto, a reference to John Romero's Daikatana.
 * Doom Guy's skateboard from Tony Hawk Pro Skater 3.
 * A painting of the Slayer holding his pet bunny Daisy, as well as a rabbit cage and a bag of food.
 * A book on "How to Comb Your Moustache" by Clifford M. Fischbach, late father of popular Youtuber Markiplier.