Half Life 2 - Orange Box

To unlock all of the game's levels, insert the following button sequence on any stage while playing the game: Left, Left, Left, Left, L1, Right, Right, Right, Right, R1.

The various grafitti in Portal can help you crack the code for the website www.aperturescience.com. Go to the website (it uses Shockwave Flash) and type in the command LOGIN.

The user name is CJOHNSON and the password is TIER3. Once you are in, you may type in HELP for a list of valid commands. Have fun!

Addition by PRO_GAMER_: You should also be able to login to aperturescience.com with the username GLADOS and the password PORTAL, as well.

Addition by red7ring: It actually doesn't matter what name you login with. You can login with any name you want. It's the password you insert that's important.

Addition by Spilled Salt: After logging in, type at the prompt "thecakeisalie" (minus the quotes). Doing so will unlock some secret messages for you to view.

Enter the code while playing Half Life 2. No specific requirements other then the game. Can be entered at any time on any level.

To get a trailer for the upcoming Valve game Left 4 Dead, wait at the game selection screen (where you choose between Portal, Team Fortress, or Half-Life 2). After a few minutes you will be taken to a demo video of the three Orange Box games. Wait for the video to end, then wait again. The next time a video plays, it will be the Left 4 Dead trailer.

Successfully complete the game to see the cake title screen.

After logging on to ApertureScience.com, type ? or LIB to see the following list of commands.

APPEND
ATTRIB
COPY
DIR
ERASE
FORMAT
INTERROGATE
LIB
PLAY
RENAME
TAPEDISK

Type DIR then type APPLY to take an application for entry into the "Enrichment Center".

While logged into the ApertureScience.com site, type THECAKEISALIE to access an interesting message left by some employees.

The graffiti in the game are clues for the ApertureScience.com web site. 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.

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.

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.