Portal/Chamber 13

Chamber 13 makes the puzzle more complex by having the solution be a two-step process; you have to press (and keep pressed) two buttons, both of which are ordinarily inaccessible. At the end of the chamber, you gain a little more insight into what GLaDOS has planned for you once you finish all twenty chambers.

First room


This first room has only a small puzzle, requiring you to fetch a cube to put on a button. Place one end of a portal on the wall above the walkway, and the other end on a wall accessible to you. Go through the portal and pick up the cube, then fall back down to the button, and leave the cube there. Now that the door's open, you can go back through the portal, through the door and into the main room.

Main room
Solving the main room requires the use of several different portals, so that two cubes can press the two buttons, opening the exit door so you can walk through.

To begin with, the energy pellet needs directing into the receiver so that the platform holding this room's cube can start moving. Place one end of a portal on the energy pellet's scorch mark on the wall, and the other where the receiver is projecting a red spot onto the ceiling. The energy pellet will go into the receiver, and the platform will start moving.

Next, you need to get the cube off the platform, and onto the first button. Place one end of a portal on the ceiling above the middle of the platform's track, and the other end of the portal on an accessible wall. When the platform's below the exit portal, fall through onto the platform, pick up the cube and walk back down onto the floor with it. To get the cube onto the button, you need to move one end of the portal you just used to above the platform holding the button — aim for the one-dot symbol on the roof. Now, go through the portal with the cube and deposit it on the button. Alternately, simply place the other portal under the cube. If placed correctly, the cube will quite possibly fall onto the button without you needing to adjust it. Where can you find another cube? Well there is another cube currently holding the first door open, however if you have portals connecting the two rooms, you do not need that door anymore. So shoot a portal into the initial room, and walk through into it. Shoot another portal (the same color as the one already in the room) that you can reach from ground level, and bring the cube off of the button and into the main room. Now place a portal on the two-dot symbol and bring the cube through to this button (or drop the cube onto the button like before). Both buttons are now pressed, and the door will open. You can jump from the button to the ledge, place portals to get yourself onto the ledge, or place a portal onto the wall of the exit room, and exit. "As part of a previously-mentioned required test protocol we can no longer lie to you. When the testing is over, you will be "missed"."

- GLaDOS

Advanced chamber
In the advanced chamber, there's only one box, and the floor is replaced by goo. Also, if you drop the box into the goo, you've failed the test.

To solve, shoot a portal at the white tile marked with one dot (through floot grating) and pass through another created portal. Get the pellet to the receiver as you normally would, and land on the box as the lift passes.

Get the box onto one of the two buttons, and stand on the second one. Get a portal on the other side of the door, and exit the map.

Portals
A 4-portal solution:
 * 1) Blue: First section, upper floor.
 * 2) Gold: First section lower floor.
 * 3) Blue: Second section, on wall next to upper red button.  Carry cube through, and jump onto lower button.  From here, throw the cube onto the lower button.
 * 4) Gold: Second section, through exit door.

Awards given at 9, 5, and 4 portals.

Steps
An awards given at 30 steps.

Time
A 24 second route involves using only the initial box to complete. Place it on the first button.

Awards given at 0:40, 0:30 and 0:19.