Portal: Prelude Test Chamber 15

This Test Chamber is the sixteenth level of the game, and introduces the players to Portal Inquisition Fields and maintenance areas.

Hazards

 * High Energy Pellets
 * Electricity Fields
 * Portal Inquisition Fields
 * Crushing
 * Cube Hazard
 * Turrets

Walkthrough
{{Spoiler|block=yes|

Test Chambr 15

 * Put the Weighted Storage Cube on the button, then go to the Switch behind the moving panel over the ledge.
 * Place portals next to the two other Switches and prepare yourself for the timed puzzle.
 * Quickly, press the Switch next to you, then the one on the other side of the ledge and pas through the portal to activate the last Switch. Then fire a portal behind and facing the Material Emancipation Grill, and the other where the High Energy Pellet is bouncing.
 * The pellet should reach the catcher. Now, grab the cube and proceed to the next room. Place the cube on one of the three buttons.
 * Go through the Portal Inquisition Field and cross the obstacle course, avoiding to be crushed as well as the Electricity Fields, in order to reach the cube.
 * Do the reverse course with the cube. '''This cube mustn't touch any Electricity Field or get crushed.
 * Place the cube on one of the two empty buttons, then go on the last one.

While exiting the Shaft
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 * Enjoy the mess then use the path that Peter opened. You are now in the maintenance areas.
 * Shoot a portal on the angled panel and the other near you then go through. Before touching the ground, place the same portal as the previous under you.
 * With the momentum you gained, you should reach the upper floor facing the angled panel. Take the cube and come back at the bottom.
 * Put the first portal in the alcove and go through the other portal with the cube. Use the two cubes as stairs to reach the hole above the alcove.
 * Knock out the Turrets carefully using portals, then go to the door at the bottom of the room.
 * Quickly, open the door, move forward, take the turret and vaporize it with the Material Emancipation Grill.
 * Go in the lift and push the little red button.

Trivia

 * The maintenance area that the player visits was already in the original Portal.

Music
11. Atmosphere 2 - 1:08 by ERH 15. Atmosphere String 1 - 2:02 by ERH