Chapter 4 - Test Chamber 21

Chapter 4 - Test Chamber 21

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This is the thirty-first level of the game, and the final part of Chapter 4. This level is set within a Test Chamber, and later the maintenance areas of the Aperture Science Facility. This level advances the central plot, and does not contain any significant Portal-related challenges.

Hazards

• Goo
• Turrets

Walkthrough

• Place a portal on the wall where the Hard Light Bridge ends and the other one on the left side of the exit.
• Go through the portal and push the Switch.
• Continue to walk to the cube.
• Put the cube on the button.

• Wait for Wheatley to open the wall and run to the Maintenance area.
• Run to the left and continue forwards.
• Turn right on just before the catwalk ends.
• Turn left and jump down. Continue by to the right up the stairs.
• Run forward as much as you can. Turn left and continue running.
• Jump down on the left side.
• Use the Bridge and run away from the Chamber until the Bridge disappears.
• Turn to the opposite direction and continue running.
• Jump from the catwalk to the area between chambers and run forward until you get to the wall.
• Pick up the turret and knock over the turret behind it.
• Turn left and go behind the tube and knock over the third turret.
• Let go off the turret (make sure it gets knocked over).
• Open a portal on the wall near the third turret. Shoot the other portal behind the panels where the third turret is. Go through the portal.
• Run to the right and follow Wheatley until a turret is revealed on the left.
• Get rid of the turret by using a portal and continue following Wheatley. Enter the elevator at the end of the catwalk.
• Wait for the elevator to stop and go through the door.

Video walkthrough

Download demo files: Part 1 – Part 2

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Related achievements

SaBOTour Make a break for it

Good Listener Take GLaDOS' escape advice

Trivia

If you go into GLaDOS's attempt to trick you back into testing, she starts talking about deer and sprays you with neurotoxin.

Music

An Accent Beyond by Aperture Science Psychoacoustics Laboratory [2:58] | Download | Play

Gallery

Wheatley interrupting the Test Chamber.   The escape begins.   GLaDOS attempts to tempt the player back to testing.