Portal Test Chamber 16 (Bonus)

This is the fourth Bonus map of the game. It is unlocked when the original Test Chamber 16 has been completed.

Hazards

 * Cube Hazard
 * Turrets

Strategy
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Portals

 * Don't use any portals to take out the turrets. Close in on them using the cubes as shields.
 * At the last turret, lean round the edge of the open door and shoot a portal through the two fences onto the tiny visible patch of portal-friendly wall.
 * Alternatively you can gather up all the cubes and use them to build steps to get you over the barrier. Jump over with a cube to disable the turret, then use your two portals to get through the final fence.

Steps

 * Use floor-to-floor portals wherever possible. Place your exit portal first, then shoot the other one at your feet and throw the exit away to somewhere else as you land.  Moving like this costs no steps.
 * From the Chamberlock, shoot a portal up to the door. Shoot the other in front of you and jump through, dumping the exit portal to the ceiling as you emerge.
 * While GLaDOS is talking, set a portal on the ceiling or wall nearby (but not directly overhead). As soon as the spiel ends and the door opens, shoot the other portal under the turret.  Then shoot the first one at your feet and you'll pop up where the turret used to be.  You'll have to run-jump over the next section.
 * When you see the next turret, aim a portal underneath it, then use floor-to-floor to get where it was.
 * Aim your portal at the floor way up at the far end of the hall and floor-to-floor again. Ideally you want to be a bit in front of the two cubes, with a clear view of the corridor between the two turrets.
 * Put a portal high up on any convenient wall and shoot the other under the boxes to drop them through onto the portal-friendly tiles. This makes them a bit easier to manipulate.
 * Use your portals to place the cubes in between the two turrets, with a gap between them big enough for you to stand in. Fiddle with their positioning until they are breaking the turret detector beams.
 * Portal yourself into the gap between the cubes and crouch. From here, take out each of the turrets in turn by dropping the cubes on them.
 * Floor-to-floor up to the end of the friendly tiles where you can see into the side room with all the cubes in it. Floor-to-floor again to get into the room.
 * Use your portals to move one or two boxes into the doorway, then portal yourself right behind them and crouch. Drop cubes onto the turrets.
 * Drop some more cubes out onto the portal-friendly tiles where you'll be able to use them, then go out yourself. Put a cube in front of the next doorway and crouch behind it.
 * Set a portal on the wall behind the turret in the far left corner and send a cube through to knock it over.
 * Shoot a portal underneath the turret on the near right.
 * If you have another cube on friendly ground, send it through to somewhere in sight of the last turret and position yourself behind it.
 * Kill the third turret by firing a portal at the security camera behind it.
 * Lift a cube and set it on the button. If you're in sight of the next turret, shoot a portal under it.
 * Aim your portal through the two fences and go through.
 * Stick a portal on the floor and chuck the last turret into it, then use portals to get right up to the Material Emancipation Grill before run-jumping to the Chamberlock.

Time

 * You can't do anything in the first 20 seconds while GLaDOS is talking - except run up to the door and get your exit portal onto the ceiling ready for the turrets you're going to send through.
 * As soon as the announcement is over, shoot a portal under the turret and get running.
 * As you come in sight of the next turret, shoot a portal anywhere on the wall behind it and the other onto the wall in front of you. Keep running.
 * Shoot your next portal up the hall and the other onto the floor and run on through. You want to be near the cubes.
 * Grab a cube and run for the nearer of the two turrets (on the left) then run on down the hall for the other one, still holding your cube.
 * Turn around and keep motoring on, knocking down the next two turrets with your cube. If the clock is much past 40 seconds by this point, you're probably not making the target of 52.
 * Drop the cube as soon as you're on friendly floor and aim a portal at the wall behind the far turret in the next room. Portal your cube through to kill it.
 * Dash in and grab the turret on the right. Try to make sure the last turret doesn't see you doing this because if it starts shooting you won't be fast enough for gold.  Barge on around the corner and knock the third turret down, then throw the other one to the floor vewy woughly.
 * Stand on the button and shoot your portal through the two fences, shoot the other onto the floor and go through.
 * Ignore the last turret - just keep running.

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