The investigation and deduction-based gameplay of Cthulhu: The Cosmic Abyss lends itself to some fun and sometimes challenging trophies/achievements. Although while you’re busy tracking down a missing deep-sea mining crew and dodging Deep Ones, it’s not always easy to keep track of them. So, here is our Open Sesame trophy/achievement guide for Cthulhu: The Cosmic Abyss.
Check out our Cthulhu: The Cosmic Abyss Review for our full thoughts on the game.
Open Sesame Trophy Guide
The Open Sesame trophy/achievement is unlocked during Chapter 6, The Last Door, and requires you to unlock a Yith mechanism using your sonar.
This is done early on in the chapter, just after entering the chamber of the last door and using the Star of Shamash on the pedestal to turn on the lights and make some stairs to get down.
The first step is locating the Prayer of the Masters pillar in the main room and analysing it to unlock the Ultrasonic Stone frequency. It’s one of the two pillars under the platform you entered the room on.
Equip the Ultrasonic Frequency and go down the staircase to the left of where you entered this large chamber to find a bridge at the bottom leading to a locked door. Analysing the door reveals details of a Song used to open the door.
Use your sonar with the Ultrasonic Frequency to unlock the door and gain access to the room beyond. This will also unlock the Open Sesame trophy/achievement.
That was our Open Sesame trophy/achievement guide! We hope it was helpful, and you can find more guides for Cthulhu: The Cosmic Abyss below.
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Cthulhu: The Cosmic Abyss Guides
- 100% Trophy Guide
- Augmented Agent Trophy Guide
- Full Charge Trophy Guide
- Artist Trophy Guide
- Against The Tide Trophy Guide
- Ph’nglui mglw’nafh Cthulhu R’lyeh wgah’nagl fhtagn Trophy Guide
- In Deep Waters Trophy Guide
- Linguist Trophy Guide
- Beyond The Senses Trophy Guide
- His Master’s Voice Trophy Guide
- Where Am I? Trophy Guide
- Better Than Pandora Trophy Guide
