Test chamber 15

Place orange portal on wall extention above and behind entrance of the first room.

Place blue portal on checkerboard tiled flooring below. Jump through blue portal. As you come out of the orange portal aim for the blue portal and enter it a second time. This will take you across the barrier.

Place orange portal on wall where energy ball bounces.

Place blue portal on wall above entry to lift. Wait for energy ball to pass through portals.

Move quickly through field and place portals on the wall and ceiling, as shown above, to faciliate the passage of the energy ball into the energy ball receiver. Ascend lift.

Place orange portal on wall extention above entrance to room.

Place blue portal on checkered floor, as close to the white sign (on the floor) as possible.
This is a tricky jump. You must jump into the blue portal and fly out of the orange portal, back into the blue portal to get to the other side. There is another way to do this jump, but this way is more challenging. To get through successfully you must jump from a distance back, into the blue portal so you only just clear its lower edge.

Place orange portal on wall extention.

Place blue portal on floor and enter portal. After emerging, reenter portal to clear the barrier.

Place orange portal on wall where energy ball bounces.

Place blue portal on opposite side. Wait for energy ball to make its passage and trigger the energy ball receptor.

Place orange portal on wall above.

Place blue portal on ground and do a double entry to make your way back across the field.

Place orange portal at end of tunnel.

Place blue portal on wall. Wait for lift to pass.

Jump onto lift.

Make orange portal at end of this tunnel, while on lift.

Make blue portal in side of tunnel as lift moves on. Continue to respawn blue portals in side of tunnel until there is a lift on the other side of the portal. When this is the case jump to it.

Make orange portal in far wall of new room. Make blue portal in side of tunnel and jump from lift into room.

Ascend slow lift on the right.

Place blue portal in wall beyond mounted button.

Place orange portal in wall in far chamber.

Press the button nearest you, then pass through blue portal and press the other button. Next place orange portal on wall extention above camera and blue portal on floor where energy ball bounces.

If successful your energy ball should enter the energy ball receptor. Ascend lift at far end of room to complete level