Part 4

Complete Portal Part 4 walkthrough, including Test Chamber 01, commentary nodes, and the button/box mechanic.

You can interact with the environment in the initial room. Using the toilet (R1) will cause it to flush and trigger a computer voice. You can lift and throw the clipboard (R2), or drop it (R1). The coffee cup can be lifted and thrown to break. The radio can be picked up but has no other function.

Turn and run through the portal.

Immediately outside the portal, turn left. Commentary Node: [Ray Raitt] discusses the player's orange jumpsuit, designed to reinforce their status as a test subject and help them stand out visually. The mechanized heel spring was added to explain the player's ability to survive long falls.

To your right, you will see a giant lighted panel that describes the hazards for each test. These panels appear in every test chamber. Turn left and follow the path.

Along the path, look up to see a Commentary Node: [Realm Lovejoy] explains that the frosted glass observation rooms create a feeling of being watched while maintaining mystery, and serve as practical light sources.

Head through the door to find a button. After entering, turn right to find another Commentary Node: [Robin Walker] explains that Portal serves as an extended player training exercise, introducing gameplay tools and layering them into increasingly difficult puzzles, starting with the button/box mechanic before introducing portals.

In this room, you will find a button and a tube that dispenses cubes. The door opens when you stand on the button, but closes when you step off. To solve this, take an Aperture Science Weighted Storage Cube (using R1, the use key) and place it on the button (pressing R1 again to drop it). Head through the now open door.

[Computer] "Excellent. Please proceed into the chamberlock after completing each test. First, however, note the incandescent particle field across the exit. This Aperture Science Material Emancipation Grid will vaporize any unauthorized equipment that passes through it - for instance the Aperture Science Weighted Storage Cube."

Head through the Aperture Science Material Emancipation Grid and into the elevator.

Test Chamber 01 (TC01)

As you proceed, the panel will light up, indicating no hazards. Head to the ledge and drop off.

Commentary Node: After falling, look to the right of the portal. [Paul Graham] discusses how players are made to feel safe within portals, with objects being pushed or teleported out as a portal closes rather than being destroyed.