Cthulhu: The Cosmic Abyss is a single-player adventure game where you play the role of Noah Williams, who is trying to find his colleague named Elsa Royer. On his journey, he finds out that Andrew Marsh and his team at Ocean-I are trying to free Cthulhu from his cosmic prison. Fortunately, there are some hints left by the Yith, the same race of aliens that imprisoned Cthulhu in the first place, to help you find a way to imprison him once again.
For more information on the game, please visit its official Steam page here.
Table of contents
The Citadel
After you activate the teleporter in the other world, you’ll be transported to a new area. Here, you’ll find Elsa, but she’s behind a wall. At least, she’s okay. She promises to find her way to you, but you have to move forward.
Stay on the path until you arrive at a broken bridge. You’ll be able to spot the star from a distance here. Jump down into the water.
Follow the source of light here and get out of the water. You’ll find a researcher here. He’ll be alive but not for long. Keep going ahead.
Keep going through the ruins until you come out on the other side. You’ll then arrive near the Citadel. The Star of Shamash is here, but it is being guarded by a gigantic guardian with many eyes.
The Guardian
There’s some organic secretion on the ground. The guardian uses the secretion to see instead of their eyes. You can’t stand on the secretion for long, because if you do, the guardian will kill you.
If you go to the left here, you’ll find a tablet written in the Yith language. You won’t be able to decrypt it yet. There’s also a green-colored stone fragment here.
If you go right from the guardian’s front eye, you can get on the tentacle leading to the lower platform, where you’ll find a body and some more stone fragments. There’s another path to the right, which leads you to a locked door.
What you have to do is go left of the eye of the guardian, where you found the Yith Tablet. Now, there’s a gap to get to the other side. You’ll notice the organic secretion floating in the air here.
There’s an invisible path that you can follow. Follow the secretion, and you’ll be able to cross to the other side. Here, you’ll find the Laboratory.
The Laboratory
There’s a macroplankton sample on the ground, directly to the left of the entrance. Analyze it and keep moving forward. There are many tanks here. You’ll have to analyze everything here.
You’ll also find another stele with the Yith language engraved on it. To translate the Yith language, you have to interact with a broken piece of a tablet. It is on the bottom floor of the Laboratory, and you’ll have to crouch down to get to it.
Once you’ve found the incomplete stele, open the Vault. There will be a deduction here paired with the previous incomplete stele that you found near the Ocean-I camp. Pair this incomplete stele with that one, and you’ll be able to translate the Yith language from now on.
One of the tanks on the bottom floor has a Shoggoth heart in it. Scan it to analyze its frequency. Now, since you’re able to translate the steles, you’ll be able to figure out what the guardian is made up of.
The Invisible Tentacles
Open your sonar and pair these frequencies: Shoggoth Heart, Macroplankton, Human Blood. Once you do so, activate the sonar to make the invisible tentacles of the guardian visible for a short duration.
You can go to the top floor of the laboratory to explore the area further. There’s an invisible tentacle here that leads to the second floor of the citadel.
As you get there, you’ll find a broken sphere. Use the frequency combination to get closer to the Star of Shamash. However, you’ll be unable to do so.
You’ll also encounter Andrew Marsh, but he’s no more. You still need to get the star because Cthulhu is close to awakening, and whatever was holding it back is growing weaker.
You’ll first need to neutralize the guardian to make it to the star. There are two ways to do so.
Corruption And Non-Corruption Paths
For the Corruption Path, you can kill the guardian by using the stone fragments and piercing the guardian’s heart. You’ll first have to coat the stone fragment in the Fallen God’s essence.
However, for the Non-Corruption Path, you can use Yith’s technology to hypnotize the guardian, neutralizing it in the process. The Non-Corruption path is a little challenging, but it’s your choice here.
Killing The Guardian
For the Corruption Path, you’ll have to stab the guardian’s heart. Use the Shoggoth Heart frequency to locate the heart. It’s on the underground floor and can be accessed by going left from the Guardian’s front eye.
However, you’ll first need to coat the stone fragment in the Fallen God’s essence, which can be done by placing the stone on some Extra-Dimensional Sap.
You can find some of it near Andrew Marsh’s body. There’s some in an alley to the left of the guardian’s main eye.
After coating the stone fragment, you can stab the guardian’s heart with it and then get the star.
Neutralizing The Guardian
From the second floor of the Citadel, use the combination of frequencies to make the invisible tentacles visible. You’ll find a tentacle here that leads to a nearby garden connected to a building called the House of Words.
You’ll find some Ocean-I researchers here, but none of them is alive. There’s a strange device with a magnetic force on one of the chests.
This is a Metal Quoit. You can use it to open chests and doors in the area. Use the Metal Quoit to open the nearby door. You’ll find an Elder’s monolith here.
One of the doors on the top floor of the House of Words is damaged. If you investigate, you’ll find out that you’ll need two Metal Quoits to unlock it.
The Second Metal Quoit
Analyze the Metal Quoit and use its frequency to locate the other one. One of the Metal Quoits will be detected behind the closed door, but this is not the one you’re looking for.
The Metal Quoit you’re looking for is located near the stairs, the one that you used to arrive near the Citadel for the first time.
It will be waiting there quietly, behind some objects. Pick this Metal Quoit and bring it to the damaged door. Now that you have two of these, you’ll be able to open the gate easily.
The Forge
There’s a forge behind the damaged door. There are a variety of metals here, but there’s also a chest. Use the Metal Quoit to open the chest, and you’ll find a tablet here.
This tablet will provide a clue that will help you deduce the correct type of metal in the Vault. Once you’ve done so, pick the bar of Zirconium from the shelves and put it into the forge.
There’s already a metal bar in the forge, so don’t forget to take it out first. Once you take out the metal bar and put the Zirconium into it, you’ll have to place the Metal Quoit on the lever.
This will give you a Zirconium sphere. Now, you have to place this orb in one of the two bases in the Citadel.
Hypnotizing The Guardian
On the second floor, you can use the Yith Alloy frequency to locate the two bases. One of the bases is destroyed by a piece of rubble that fell on it.
The other can be reached by walking over an invisible tentacle. Once you get to the second base, place the Yith Orb: Zirconium inside it.
This will unlock a cutscene where the Guardian becomes neutralized. It won’t harm you anymore, and you can freely walk on its tentacles. Now, use the combination of frequencies to make the tentacles visible again and get to the Star of Shamash.
Once you get to the top, interact with the star to obtain it. This will end Chapter 5, and you’ll be teleported to the Final Door.
This concludes the walkthrough for Chapter 5 of Cthulhu: The Cosmic Abyss.
If you’re looking for more walkthroughs, please visit the game’s main hub here. You may also like the following pages:
- Into Indie Games Homepage
- Pragmata Complete Walkthrough Hub
- OPUS: Prism Peak – Walkthrough Hub
- DarkSwitch – Walkthrough Hub
- The Occultist – Complete Walkthrough Hub
Fahad Suleman is an avid fan of fighting games who spends most of his time writing walkthroughs and reviews for cozy indie titles or mashing around in Tekken. If he’s not writing or playing any games, you’ll often find him watching historical videos on YouTube for hours.
