Portal 2 Chapter 4 Test Chamber 21 (Escape)

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This is the thirtieth level of the game, and the final part of Chapter 4. This level is set within a Test Chamber and 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
 * Neurotoxin

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Intended Chamber Solution

 * 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.
 * Use the portal again to proceed to the chamber lock.

Actual Course of Action
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 * 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.