Part 39

Test Chamber 16 (LT16): Goal: 1m 10s, Gold: 52s. Wait for voiceover, place portal above door. After voice, run through, place portal at turret base, run through. Enter hole, place portal at hall end. Place other on wall, run through. Place portal on far wall, other in front, run through. Grab box, position it. Use box to knock down turrets: first left, then second down hall, then two in large room. Shoot portal at far left corner (behind turret) and other on ground below box to knock down turret. Grab another turret, use it to knock down the last one. Stand on button, aim through grates, shoot portal at wall near you, run through. Enter chamberlock.

Test Chamber 17 (LT17): Goal: 2m 20s, Gold: 1m 27s. Jump constantly. Wait for cube, bring to next room, place on ledge, jump. Pick up cube, use to reach next ledge. Hold box to block energy ball while running down hall. Descend stairs. Jump onto stairs, turn, let ball bounce off box. Continue backwards, descend stairs. Enter big room, throw box near pistons. Portal camera on left door, other on camera near stairs. Grab camera, jump down, place in indentation with pistons. Place other camera on top, then box on top of cameras. Jump up to ledge. Crouch, grab box, bring upstairs. Place box on button, enter small room, press button. Run out, drop box in incinerator. Enter chamberlock.

Test Chamber 18 (LT18): Goal: 2m 10s, Gold: 1m 13s. Jump instead of run. Run onto small ground piece above water. Portal ceiling above far ground, other at feet. While falling, portal right to white ground. Portal large white wall, jump through. Portal ceiling above next ledge, other at feet. While falling, portal feet, then portal far pushed-out concrete on high ledge. You'll be in a small room behind a large button. Press smaller button. Quickly exit right side. Aim for slanted surface, jump off ledge right, portal where you would land to fly to box area. You will be shot but likely survive if quick. Grab box, jump off edge facing away. Hold analog stick backward to land on ledge below. Drop box, place portal on white wall.