Level select
While playing the game, press Left(4), L1, Right(4), R1 to unlock all levels.
Create box
While playing the game, press Down, Circle, X, Circle, Triangle, Down, Circle, X, Circle, Triangle.
Fire energy ball
While playing the game, press Up, Triangle(2), Square(2), X(2), Circle(2), Up.
Alternate title screen
Successfully complete the game to unlock the cake title screen.
ApertureScience.com login
The graffiti in the game are clues for the ApertureScience.com website. Go to the site, and enter "LOGIN" as a command. Enter "CJOHNSON" as a username and "TIER3" as a password. After logging in, type "HELP" for a list of commands. In addition to logging in as "CJOHNSON" (Chell), you can login as anyone desired by typing a username longer than two characters and using "PORTAL" as a password.
ApertureScience.com hidden message
While logged into the ApertureScience.com website, type "THECAKEISALIE" to access a hidden message left by some employees.
Completing Chamber 18 easier
At the end of the advanced map for Chamber 18, you will have the same raised platforms as you did in the normal one except now after you leave the lower one, it falls into the toxic water. This forces you to be more precise with your portal jumps. However, you can get past this easily. Do the platform jumping as usual, but if you miss, just land on the platform you came out of. You should be able to fire an opposite color portal at the wall where you entered this area, allowing you to go back to the start. All the platforms rise again, and the portal is still where you left it. You can now fall into the pit again and be able to portal jump to the next ledge. This take longer but does not require precise timing.
Box head pictures
On the level where you get the companion cube after you run past the energy balls and are in the room with the three elevators, there are two doors leading to a catcher and a platform that is pushed out of the wall. Walk up to the platform that is pushed out. Crouch behind it, and walk through the opening. On the left hand side are a group of pictures of people with boxes for heads and hearts around them.
