How to reach the Underpass
The story opens this depth during Recursions and Iterations, after Enemy of My Enemy. Meet Pope in the Oldest House lobby, then revisit the laundromat route used to leave the Sinkhole. Continue through the back, descend past the PERSONNEL ACCESS platform, and follow the yellow tape, arrows and white lamps on ropes.
Activate the Sinkhole fast-travel door. The former diving-bell area now has a deeper opening. Descend through it and follow the lit stairs. In the Underpass, land on the red platform and follow the lamps to the right. This route uses Shift on altered surfaces; obtain Reach from The Subway Fault before attempting its later grapple gaps.
Lit corridor descent · 0:55 ▶ · Cross the chasm · 1:39 ▶
Find the right Underpass destination
| Destination | Route | Purpose |
|---|---|---|
| The Spire | Follow the white lamps up the pillar field. Activate the door at the upper camp. | A useful travel anchor; climbing the Spire leads to the Astral Plane Resonant. |
| Map Kit | Look below the Spire platform, behind its fast-travel door. Clear the nearby Hiss, then visit the dishes and central tower. | Reveals the regional map; it does not complete either Fault or Resonant. |
| Halfway Trail | Continue along the lower research route beyond the Map Kit. | Save a travel point before the Reach-dependent crossing. |
| Research Station / Research Site | Continue toward the research expedition and its marked time fluctuations. | Recursions and Iterations follows the researchers, equipment and later relay trail. |
| Tubes Island / Fault | From The Spire, grapple across the islands toward the orange pipes; activate the Fault door. | The Underpass Fault: a Jesse sighting, separate from the Spire boss. |
Orange pipes or the Spire?
The Underpass Fault leads into the orange-pipe island on the west side of the region. Use the Reach anchors from The Spire, clear the Mold on top, then circle to the gap on the island’s west/back side. Continue through its interior toward the bright room and television.
The Underpass Resonant starts at The Spire and leads upward into the Astral Plane. Track the named objective before climbing: a Jesse sighting and an Astral boss are different routes.
If the island looks close but the jump is impossible, check Reach first. It grapples designated spheres; Shift changes your orientation on suitable surfaces. Completing the Underpass Fault is also required for The House in Distress. For the projected-children puzzle and Jesse’s ritual, follow the full Underpass Fault walkthrough.
Pillar field · 2:03 ▶ · Upper approach to the Fault · 4:08 ▶
Reveal the regional map
From The Spire, look down over the floating columns for the central Pylon and three satellite dishes. Work around the columns, interacting with each sensor until its red light becomes green. Return to the central red-carpeted platform and activate the tower panel last. Check for Zone Map Unlocked and reopen the map.
A red light means a sensor still needs calibration. Three green lights with a blank map means the final tower interaction is still missing. This is exploration hardware, not an item to buy.
Useful tasks in this region
Keep Recursions and Iterations tracked when following the expedition. After collecting Grist’s device, its markers distinguish the time fluctuations. Later sections return to changed research sites, then the transmission tower, Cable Car and final probe relay. Changed camps are part of the story’s timeline shifts.
Unsupervised Science and Freeze Frame have separate regional objectives. Use their dedicated entrance and camera routes after reaching the area; a revealed map is not a completed collection.
Saved on this device. These marks do not read your game save.
Watch the entrance route
Select a chapter to play it here.
Watch on YouTube ↗This recording continues into the Fault and contains story spoilers. The time links above play the approach in this page.
Sources & image credits
Sources, gameplay and image credits
- PowerPyx · Recursions and Iterations ↗ — story access, lamps and travel doors
- PowerPyx · The Underpass Fault ↗ — Tubes Island, Reach and the rear entrance
- PowerPyx · The Underpass Resonant ↗ — Spire objective and Astral Plane
- Method · Underpass Fault ↗ — traversal prerequisites and separate boss route
- AllThingsHow · Underpass Map Kit ↗ — sensor and Pylon sequence; WoW Quests frame
- Emmie Jacob Game Guides ↗ — Sinkhole approach at the captioned times
- Whisper of the House · Underpass ↗ — research-team route and timeline context
Checked October 8, 2026. Selected gameplay frames retain the creators’ marks. Recording build numbers are not visible.