- "Sector Horologium appears to reflect the instant of Earth's creation. Divine light shines in like the morning sun and the glow of magma seeps from the cracked ground..."
- —Black box data, Shin Megami Tensei: Strange Journey 
Sector Horologium is the final (eighth) area or sector that the Red Sprite's crew investigate inside the Schwarzwelt.
Sector Horologium is a massive maze of superheated magma and roaring skies, filled with Mem Aleph's defenders and the remaining elite armies of The Three Wise Men. Shortly after arrival, Arthur is knocked offline and remains unresponsive. Then, the ghostly voice of Commander Gore blasts through the speakers, bidding the Red Sprite's crew to leave their ship and join him in Horologium's deepest chamber, the lair of Mem Aleph herself.
Upon reaching Gore in Horologium B9F, he guides the Protagonist to the chamber and shows him Mem Aleph, but the Protagonist lacks the necessary "brilliance" to see her, and all he sees is a huge mass of energy congealing in the cavern. Upon exiting, Gore creates a spatial warp to transport them both to the safety of the Red Sprite.
Once there, he proclaims he has seen the future of Humanity, but that it's a future that will never unfold unless the Schwarzwelt is stopped at its core and destroyed. He pleads with the crew to take the right choice, and talks to the Protagonist about his stance and alignment; depending on the answers, this leads to any of the three alignment choices for the sector.
Gore confronts the Protagonist when it becomes obvious he will defer to the angels and dies at his hands, and laments as he fades away how Humanity has been delivered into the hands of the God of Law's servants, The Three Wise Men. Zelenin attacks the Red Sprite with her song, obliterating the spirits of the crew and rendering them submissive servants of the Lord. Arthur's circuitry is damaged and to prevent the catastrophic loss of data, the AI deletes itself to give space to more valuable life and transport systems.
Zelenin informs the Protagonist of the Cosmic Eggs, small containers of huge energy stores capable of creating a new world when used in conjunction with Horologium's Exotic Matter. After these have been collected, the demonic forces mass on Horologium, desperate to stop the angelic plan, even resorting to destroy Horologium's main elevator shaft, and posting a Surt to stave off invasion. Despite, fighting the demonic Soil Jimenez, the Protagonist reaches Mem Aleph's inner sanctum in Horologium B9F. In there, the formless entity is forced into her true shape by Zelenin's song, and promptly attacks the Protagonist, and when her initial form falls, is reduced to engaging him as Empty Mem Aleph, an embryonic entity representing naked power. Falling despite this massive power augmentation, she weeps for the creation of a world of empty law that she deems as just another form of absolute death.
Following her demise and the collection of Horologium's Exotic Matter, Mastema meets the Protagonist and Zelenin at the Vanishing Point, blessing their efforts as the World of Law comes into being.
An additional mission can be reached if the Protagonist has spoken to a certain Archangel in Sector Grus. He will point the Protagonist to a ritual being carried out in Horologium to summon a powerful angel, a Seraph. If the Protagonist chooses to visit the site, the Seraph will be born and will issue an EX Mission, asking him to kill Mara, the Mother of Temptations, in Grus.
Gore is slain at the hands of the Protagonist after lamenting in death that humanity has sold itself to the demons. With his defeat, Jimenez attacks the Red Sprite and unleashes energy beings similar to the Delphinus Parasite, ensuring the crew's full cooperation. Jimenez deems this as a boon anyway--he refers to the madness the Parasite awakens as being genuine freedom. Arthur is damaged beyond repair in the struggle, and chooses to delete its personality matrix rather than waste valuable space in the computer to allow all other systems to remain intact.
Jimenez explains how to complete the Schwarzwelt's original purpose: gathering the Cosmic Eggs, small orbs of pure energy, and taking them to Mem Aleph, the Mother of the Schwarzwelt. Desperate to stop this, the angelic forces throw everything they have against the crew, destroying the main access to Mem Aleph but humiliatingly losing Israfel at Horologium 1F and Mastema in Horologium's underbelly in the process. Louisa Ferre stops by to mock Mastema for being a twisted and corrupt Angel and to wish the Protagonist good luck before disappearing.
Upon reaching Mem Aleph anyway, she kills herself and pours her essence into the Cosmic Eggs. Jimenez then reveals the last phase of the plan: once the Eggs have been shunted into the Vanishing Point in Sector Eridanus, the Schwarzwelt will expand and swallow the Earth.
Upon reaching the Vanishing Point, an empowered Zelenin fights for her beliefs. However, even after her transformation into the colossal Pillar Zelenin, she loses as Jimenez negates her song and the Protagonist blasts her into oblivion, and the World of the Gods of Old is restored: a world of Chaos and brutality.
Another EX Mission will be available if the Protagonist has spoken to Grendel in Sector Grus again after the demise of Commander Gore. Referring the Protagonist to Maya's former chamber, Mara, its then-occupant, will issue a mission to find and destroy the ritual to summon a massive angelic superweapon, Seraph, upon Horologium. The ritual is unstoppable, and Seraph must be fought in its full glory. However, upon its death, Mara will appear, lamenting she did not participate in the Seraph's death, and will offer to joint the Protagonist after granting him the best gun of the game.
The Neutral Path, as per series tradition, is the hardest; Gore, instead of fighting, praises the crew for standing up to their beliefs and begs them not to take heed of the demons' power or the peace the angels offer, but to find the true freedom Humanity wants and needs. With this, he empowers the protagonist with his "brilliance", beams a stream of information into Arthur, and fades away.
Arthur proclaims he has an alternative to the plans of either the demons or the angels; the Gigantic carried a nuclear artifact, and with it, along with the Cosmic Eggs and Horologium's Exotic Matter, it is possible to destroy the Schwarzwelt and restore Earth. However, this of course means open war with both the forces of Chaos and the armies of Law, forcing him to fight for each Egg, including killing Judge Zelenin at Sector Bootes. A terrified, morose Mastema briefly appears to condemn Zelenin's death, but chooses not to engage in combat.
Once all four Eggs have been collected, the assembled armies of both sides will destroy Horologium's main elevator shaft, leaving a Skadi as a guard. Later, fighting past Horologium's defenses, the protagonist will find and confront Awake Jimenez, killing him to proceed onwards; as he dies, he acknowledges the protagonist as a better person than him. Arthur, slowly weighed by the experiences he's accumulated, says:
- "This is Arthur speaking. I have verified your victory over Jimenez. [Player], I understand the pain of having to eliminate a former comrade. I will not tell you to forget it. So long as you continue to live alongside humans capable of sin, it cannot be avoided. But I am partially responsible for leading you down this path. Like you, I am an entity that bears sin. The only way to atone... is to succeed at our task. [Player], continue your mission."
Proceeding further onwards, Mem Aleph wakes from her sleep in Horologium BF9. She is fought both as Mother Mem Aleph and Empty Mem Aleph. Once her energy and her Exotic Matter are secured, the Red Sprite is taken to Eridanus' Vanishing Point.
As the ship enters the dimensional rift, Arthur announces he does not wish to go back to civilization, as the godly knowledge Gore gave him has convinced him Humanity would come to misuse his immense power and worship him, something he finds unacceptable as his main imperative is to ensure Humanity's best interests and ensuring they never lose control of their destiny. Instead, he asks the Protagonist to bequeath him the "brilliance" Gore gave him as to allay his fears and to download his personality matrix into the nuclear artifact.
Honoring his wishes, Arthur is given the "brilliance" and placed into the bomb.
Soon after, the bomb detonates, destroying the Schwarzwelt and knocking the Red Sprite back into Earth's South Pole, leaving the story of the events within to them to tell...
Demons appearing in Sector Horologium include:
- Kama (Enemy Search)
- Nergal (Enemy Search)
- Seth (Enemy Search)
- Samael (Enemy Search)
- Trumpeter (Enemy Search)
- Jimenez (Boss; Law Path and Neutral Path only)
- Mastema (Boss, Chaos Path only)
- Mem Aleph (Sector Boss, Final Boss of Law and Neutral Paths)
|Characters||Protagonist - Gore - Jimenez - Zelenin - Arthur - Bugaboo - Captain Jack (& Jack's Squad) - Ryan - Mastema - Louisa Ferre - The Three Wise Men - Mem Aleph - Kato - Williams - Muccino - Irving - Chen - Terry - MacCleary - Dent - Mia - Gekko - Anthony - Blair - Zoe - Maebe - Wolf - Tyler - Mackie - Mike - Dawson - Keema - Norris - McClane - Alex|
|Locations||Red Sprite - Sector Antlia - Sector Bootes - Sector Carina - Sector Delphinus - Sector Eridanus - Sector Fornax - Jack's Squad HQ - Sector Grus - Sector Horologium - Wailing Womb|
|Terminology||Schwarzwelt - Demonica - Demon Summoning Program - Delphinus Parasite - Magnetite - Macca - Moon Phase System - Cosmic Egg|
|Lists||Demons - Bosses - Skills - Forma - Equipment - Items - Apps - Extra Missions|
|Music||Shin Megami Tensei: Strange Journey Original Soundtrack|