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Once the two Companion Cubes have been disintegrated by GLaDOS, place one between the beam to break it, lowering the platform behind you.

Place a portal directly under it and once you’re standing on the platform, fire off the exit portal at the vertical wall behind it to re-engage the beam, taking the platform upwards to the next floor.

At the top you’ll notice two angled walls on your left. Fire a portal at the angled wall farthest away and then drop back down towards the Companion Cube.

Walk back through the portals and you’ll reappear with the Cube on the upper level of the chamber. Drop the Cube down by your side and then look back down towards the beam below you.

Look for what colour the portal is below you and change its location so it’s facing upwards. Pick up the Companion Cube and fall down towards the portal, you’ll fly out of the angled wall towards the red button.

Replace the portal that was on the right-hand angled wall onto the left-hand wall and fall back down into the portal below you.

You’ll gain enough momentum to come out at the top right towards the exit!

Missable Achievement/TROPHY ALERT!

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Preservation of Mass

Break the rules in Test Chamber 07

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Guide Information
  • Publisher
    Valve Corporation
  • Platforms,
    PC, PS3, XB 360
  • Genre
  • Guide Release
    30 June 2011
  • Last Updated
    7 December 2020
  • Guide Author

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Welcome back to Aperture Science, a world where your Companion Cube isn’t you’re only company. Take control of Chell once again in Valve’s sequel which takes you on an humorous and puzzling adventure and in our detail-packed guide we’ll show you:

  • How to solve every test chamber first time.
  • Conquer every co-op chamber with a friend.
  • Loads of High Definition screenshots and videos showing you the solutions to every single chamber.
  • High Definition strategy videos for every achievement in the game.
  • Uncover all of the hidden secrets and Easter eggs.

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