Maintenance Protocol: Three Bulbs and the Exit
After Zoe’s Briefing, investigate the Oldest House door near Deepest Underpass. Use the projector-room console to reveal three bulbs, repair them, then return and finish the final projection.
Quick answer
After Zoe’s Briefing, investigate the Oldest House door near Deepest Underpass. Use the projector-room console to reveal three bulbs, repair them, then return and finish the final projection.
On this page
Open the maintenance assignment
Speak with Zoe at Central’s Watchtower during Zoe’s Briefing. In Underpass, travel to Deepest Underpass and look south for the climbable ledge and Oldest House door. Inspect the door, use the adjacent entry panel, clear the Mold inside and follow the passage to the projector.
Let the briefing finish. Use the nearby console beside the three red lights to add the bulb markers. If the map has no maintenance targets, check this console before searching the entire region.
Match the repair to the symptom
| Bulb | Landmark | Required action |
|---|---|---|
| Electrosensitive | Below Research Stations | Move all three nearby Charges away into lower receiving cores before touching the bulb. |
| Volatile | East of Halfway Trail | Calm it, defend it from Hiss, then complete the reassuring conversation. |
| Botanophobic | Island north of Research Site | Destroy the surrounding Mold and interact with the exposed bulb. |
For the electrical bulb, use the lower cores northwest and west of its platform, including the receiver beyond the second one. Leaving one charged core beside the bulb prevents the repair.
Volatile bulb dialogue
- Begin with “You’re okay.”
- Defend the bulb and choose “I’ll keep them away from you.”
- After the attackers are defeated, choose “You deserve to be fixed.”
- Approach and complete the repair interaction.
Return for the final bulb
Travel back to Deepest Underpass and revisit the projector room. Interact with the final bulb in the projection. To leave the slides, choose “Where are you going?” → “Unstable bulb” → “Do you know a way out?” → “Break the bulb.” Check the quest completion and the Standard Issue Coverall in your outfit collection. Fixing the three map markers is not the last objective.
Before you leave
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Sources and scope
Written walkthroughs compared November 3, 2026. The diagrams explain the operation order; no site playthrough or performance benchmark is claimed.