【Tales of the Neon Sea Walkthrough and Guide】Chapter 4.1：Wake Up. The Nightmare is Real

Rex Repaired

After the cliffhanger ending of Chapter 3, you'll regain control of Rex inside the Sewage Maintenance Room... where we last left him all the way back in the Prologue! Boy howdy, that felt like a lifetime ago.

Leave the Maintenance Room, then climb up the ladder to follow William and head through the doorway.

Now continue all the way right and enter the Elevator at the end of the hall.

Abandoned Underground Factory

Step off the Elevator when you arrive at the Abandoned Underground Factory, and head right.

Climb down the ladder, then jump across the suspended storage boxes to continue going further right.When you reach the other side, inspect the nearby broken tanks if desired. Otherwise, jump left across the gap.

Head inside the nearby Steam Control Room.

After another chat with the AR Captain inside, grab the Main Valve Wrench and Broken Emergency Lamp to the left of the entrance.

Then grab the Air Lock Device from the far right side of the room.

Use this Air Lock Device to seal off the valve on the far left pipe inside the Steam Control Room.You should notice an indicator light turn on above the main pipe. Leave the Steam Control Room, and jump across to return to the right platform where you saw the broken tanks. Use the Broken Emergency Lamp on the middle cracked tank.You'll obtain a Bottle of Volatile Fluid. Jump back across to the left, and use this Bottle of Volatile Fluid on the Fungi Mass at the indicated hotspot.This clears away the fungi, but not the spore cloud. First, inspect the deactivated robot that you just uncovered near the ladder leading down. You'll obtain another Air Lock Device!Head back into the Steam Control Room, and use this second Air Lock Device on the valve to the right of the main pipe.

This should redirect all steam to the main pipe leading outside. Go back out and use the Main Valve Wrench on the (you guessed it) main valve just to the left of the room entrance.This clears out the dense spore fog, allowing you to explore the bottom levels at last. Head down the ladder and approach the green doorway you see to the right. You'll unlock another Achievement!

That means you're on the right track. Head through the door to enter the Ventilation Chamber.