Portal Chapter 10 (Puzzle 18)
Walk forwards to the edge of the pit and then place a portal on the ceiling on the other side. Place a portal in the floor or wall and drop through to the other side.
Place a portal on the next highest ceiling and then one in the wall on the other side of the narrow pit. Jump through it to land on the ledge above.
Place a portal on the extended tiles above the level exit, then the second portal on the floor below you and go through.
As you’re falling place a portal where you’re going to land and you’ll go through the portal again, this time getting flung across the gap.
Press the little red button to extend the vertical platform a little so you can look out. There are a few guard droids that you need to deal with before stepping out into this large room.
A rotating light ball shooter will shoot balls of light against the walls. Place one portal where the light ball is about to hit and the other opposite one of the droids.
Continue doing this for the other droids until they’ve all been knocked off their platforms. Once the coast is clear you’ll need to bring the ball of light into the receptacle in the little room to the left.
Place a portal on the extended tiles on the wall opposite the little room and the other portal on the wall where a light ball is about to hit.
Once the light ball has gone through the portal place a portal next to the raised little red button on the left and one on the wall next to you. Quickly press the little red button to open the door and let the light ball through to the receptacle. This activates the central platform.
Take the platform across to the other side and drop down. Place a portal back near the entrance to this room and one just around the corner from the little red button. Press the little red button to extend the tiles back at the entrance to this room and go through the portal.
Place one portal on the extended tile and drop off the edge to the right. Place the second portal beneath you and you’ll be flung across the room to the alcove with the cube.
Pick up the cube and take it across the platform to the other side. Drop the cube by the entrance and place a portal near to the entrance. Go back over the platform and drop down by the little red button. Press the button and go through a portal back to the entrance. Grab the cube and leave the room.
Place the cube on the red button to open the door opposite. Place a portal on the other side and one on one of the platforms below you. Go through the portal and then through the open door.
Ahead is a series of platforms and to the left is a pit. Place a portal on the first platform ahead and then one at the bottom of the pit on the left. Drop down the pit and you’ll come flying out of the platform ahead.
You’ll need to place a portal on the next highest platform while you’re in the air and then the second portal below you. Continue doing this as you progressively get higher and higher.
When you’ve made it to the highest platform you’ll need to shoot a portal on the sloped tiles opposite the exit. Place a portal beneath you and you’ll go shooting out towards the lift.
Next: Portal Chapter 11 (Puzzle 19)