AETHUS Hidden Achievements Guide: All 21 Secret Trophies

AETHUS contains 21 hidden achievements out of 40 total Steam achievements, focusing primarily on main story facility progression, companion events, keycard collection, and secret exploration areas throughout the underground caverns and Magma Rifts.

Complete List of AETHUS Hidden Achievements

Steam hides 21 of the 40 achievements in AETHUS to avoid spoiling narrative beats, abandoned facility locations, and story outcomes. The three-column table below outlines every hidden achievement, where it triggers, and the exact objective required to unlock it.

Story Facilities and Keycard Achievements

Most secret achievements register automatically as you work through the abandoned research stations left behind by the Astral Resource Corporation expedition. Four primary achievements require securing specific personnel keycards from designated complexes:

• Artificial Unintelligence: Unlocks when you retrieve Dr. Harlow’s keycard inside Facility Epsilon. In that facility, proceed past the climber into the Cargo Bay and access the Loadmaster's Office.
• Mu-ving On Up: Triggers upon taking Lisa Chapman’s keycard inside Facility Mu.
• Body Engineer: Awarded after picking up Dr. Sinclair’s keycard inside Facility Theta.
• Hero of the Spooky Underground Jungle: Unlocks when you install a replacement reactor within Facility Lambda to stabilize the sector.

Advancing through the final zones leads directly into the third biome, the Magma Rifts, unlocking Getting Warmer. Toward the narrative climax, following the main objectives takes you inside the final research base for Alpha to Omega, before triggering the final campaign credit sequence and granting the ending achievement, Time is a Flat Circle.

Companion and Construction Secret Trophies

Companion interactions and base installations form another category of secret milestones. Maeve begins her claim accompanied by an AI drone companion named Roland, but story events separate you during the expedition. Reconnecting with your drone awards Best (Robo) Friend.

Two additional companion achievements center around Stanley:

• The Kappa Module: Granted when you investigate Facility Kappa and uncover the background regarding Stanley.
• Successfully Returned: Unlocks after you transport Stanley back up to your surface Outpost and complete his reactivation sequence.

Base construction also features dedicated secret milestones. Assembling the Scarpa Climber’s Surface Station grants Going Down, which establishes your transit deeper into the planet. Later, assembling the Covert Comms Tower at your camp fulfills the objective for It’s covert, honest!. Producing technical items at your workbenches through specialized recipes similarly awards Remote Override as soon as you assemble an EMP Charge.

Hidden Exploration and Discovery Achievements

A few hidden trophies reward checking off-path tunnels rather than running directly along quest markers.

The Outer Caverns contain two specific exploration milestones:

• Always Something Behind the Waterfall: North-East of Facility Delta, locate an operating drill positioned before a waterfall. Walking behind the cascade reveals a concealed cave passage. Reaching the interior registers the achievement. This location also holds the Jenkins (Beach) plushy variant.
• Shortcuts: Found by locating the hidden passage that links the Outer Caverns directly to the planet surface without backtracking through standard ascents.

In the deepest subterranean biome, locate the massive suspended formation in the cavern to unlock CRYSTAL CRYSTAL CRYSTAL. For audio lore, interacting with any recorded playback console awards Echoes of the Past on your initial listen.

Players tracking achievement completion do not need to worry about combat or resource difficulty settings. The Steam guide created by Leyren confirms that difficulty presets and custom modifiers have zero impact on achievement eligibility, so you can freely select the best difficulty settings for your personal playstyle. None of the 21 hidden achievements are permanently missable during a single playthrough, as unfinished exploration objectives and story facilities remain open before concluding your campaign walkthrough.