You start in a dark kitchen. Go through the door, then turn left down the hallway. Turn left again onto the stairs, then climb up the stairs to the top.
Continue through the next few doors until you reach a balcony. Wait for the walls to open, then teleport to the railing and teleport back to the platform below. Proceed through the bedroom into the next room.
Go through the next door to find yourself in a house where gravity seems to have stopped working properly. Walk along the right wall, then teleport to the dining room table and into the foyer. A dead poison crab will fall to the floor next to your face, but it won’t harm you.
Travel through the next apartment until you reach the kitchen with the floating dishes. Go through the kitchen and enter the door on the left into a dark hallway.
Turn right at the end of the corridor and approach the corpse leaning against the window. Dead headcrabs will jump out of the floorboards, but you can ignore them.
Follow the corridor to the end, then tear up the loose floorboards and drop down into the room below. Click on the next door, and you’ll find yourself in another mirrored room. You can explore the apartment as much as you like, but eventually the front door will open on its own, allowing you to teleport through.
On the other side, you’ll see the inside of the Vault from the catwalk. Turn around and walk into the corridor. Use your VR controllers to point your hands at the nodes and press the grapple button, then press the grapple button again to release what appears to be Vortigone’s green lightning ability.
Use your newfound ability to blast open the door and kill the Combine soldiers inside. Each of your lightning attacks will kill everything it touches, but you can still take damage, so it’s worth taking cover and using the healing syringes left by the dead Combine soldiers. Proceed down the hallway until you reach a long corridor lined with grenades.
In this section, simply activate the grenade and move your wrist in the direction you want, and momentum will take care of the rest, gently transporting the explosive payload to destroy the soldiers at the opposite end of the corridor. This is the very last section, so go through it and use the nearby medical station if you need it.
