- Achievements
Do the following things to obtain the corresponding Gamerscore points:

2 Points
Two Points	Use DOG's ball to make a basket in Eli's scrapyard.
5 Points
Hack Attack!	Kill five enemies with a Manhack.
Heavy Weapons	Get the airboat's mounted gun.
Turret	Accumulate 10 turret kills with a single turret.
Head of the Class	Play a complete round with every class.
Attica!	Destroy the gunship in the hospital attic.
Anchor's Aweigh!	Get the airboat.
Grey Matter	Get 25 headshots as a Sniper.
Into the Breach	Help Griggs and Sheckley keep pushed off the Antlion invasion inside the mine shaft.
Acid Reflex	Kill an Acid Antlion worker.
What cat?	Break the mini-teleporter in Kleiner's lab.
Targetted Advertising	Pin a soldier to the billboard in chapter Highway 17.
One Man Army	Destroy six gunships in Half-Life 2.
Team Doctor	Accumulate 25000 heal points as a Medic.
Barnacle Bowling	Kill five barnacles with one barrel.
Pedal to the Metal	Clear DOG in a race to the White Forest base.
Watch Your Head!	Make it to the bottom of the Citadel's main elevator shaft in one piece.
World Traveler	Play a complete game on every map.
Conservationist	Kill five enemies with the same energy ball.
Camera Shy	Detach security cameras from the walls.
Flushed	Kill an enemy with a toilet.
Containment	Contain the Citadel core.
Malcontent	Escape the apartment block raid.
Partygoer	Make the correct party escort submission position decision in Portal.
Long Jump	Jump 300 feet in Portal.
Flamethrower	Set five enemies on fire in 30 seconds.
Car Crusher	Use the cars to squash 15 antlions in Half-Life 2
Lab Rat	Acquire the fully powered Aperture Science Handheld Portal Device in Portal.
Gordon Propelled Rocket	Unlock the rocket launcher lambda cache in the Under The Radar chapter.
Counter-Sniper	Kill all of the snipers in City 17.
Hit and Run	Run over 20 enemies with the car in Half-Life 2
Zombie-que	Use flares to light 15 zombies on fire.
Grave Robber	Steal a Zombine's grenade.
Bone Breaker	Kill 30 enemies with thrown physics objects.
Powerhouse Offense	Be victorious in 2Fort with a shutout.
Trusty Hardware	Get the crowbar.
Terminal Velocity	Fall 30,000 feet in Portal.
Deadly Harvest	Kill an enemy by planting a hopper mine.
OSHA Violation	Kill 3 enemies using the crane.
'Radiation Levels Detected'	Get through the toxic tunnel under City 17 in Half-Life 2.
Fratricide	Do whatever it takes to survive in Portal.
Zero-Point Energy	Get the Gravity Gun in Black Mesa East.
Pinata Party	Find and break every web cache in Half-Life 2
Nemesis	Get five revenge kills.
Friendly Fire	Knock down a turret with another turret.
10 Points
Revenge!	Destroy the hunter-chopper in Half-Life 2.
Follow Freeman	Gain command of a squad of rebels in the uprising.
Lightning Offense	Be victorious in Well in 5 minutes or less.
Heartbreaker	Finish Portal.
Basic Science	Gain bronze medals on all Portal challenges.
Dynasty	Be victorious in 20 games.
Atomizer	Disintegrate 15 soldiers by throwing them into a Combine ball field.
Cache Checker	Find every radar cache in the Under The Radar chapter.
Blast from the Past	Find the HEV Suit Charger faceplate in Eli's scrapyard.
Cupcake	Clear two Portal advanced maps.
Live Bait	Help Alyx snipe 30 enemies in Half-Life 2
With Friends Like these...	Play in a game with seven or more players from your friends list.
Impenetrable Defense	Successfully defend Dustbowl without giving up a capture.
Hot PotatOwned	Kill a Combine soldier with his own grenade.
Pacifist	Contain the Citadel core without killing any stalkers.
Giant Killer	Survive the rooftop strider battle in the ruins of City 17.
Bug Hunt	Use the antlions to kill 50 enemies.
Payback	Kill a Hunter with its own flechettes.
Plaza Defender	Survive the generator plaza standoff in chapter Anticitizen One.
Fight the Power	Shut down the supression device by disabling its generators.
Think Fast!	Kill an Elite Soldier with his own energy ball.
Warden Freeman	Survive the second turret standoff in Nova Prospekt.
Hard to Kill	Get five kills sequentially without dying.
Elevator Action	Survive long enough to get on the parking garage elevator.
13 Points
Vorticough	Discover the hidden singing vortigaunt cave in chapter Water Hazard.
15 Points
Puttin' On a Clinic	Overcome the chopper in Half-Life 2
Hardcore	Accumulate 1000 total kills.
Citizen Escort	Don't let any citizens die when escorting them to the escape train.
Master of Disguise	Trick an opposing medic into healing you.
Lambda Locator	Find all lambda caches in Half-Life 2.
20 Points
Fruitcake	Clear four Portal advanced maps.
Get Some Grub	Squish every Antlion Grub in Half-Life 2
Relentless Offense	Be victorious in Hydro without giving up a capture.
Rocket Science	Gain silver medals on all Portal challenges.
Escape From City 17	Escape City 17 with Alyx.
Keep Off the Sand!	Cross the antlion beach in chapter Sandtraps without touching the sand.
25 Points
Zombie Chopper	Play through Ravenholm using only the Gravity Gun.
30 Points
Little Rocket Man	Send the garden gnome into space.
Vanilla Crazy Cake	Clear all six Portal advanced maps.
Impossible Defense	Successfully defend Gravel Pit without giving up a capture.
35 Points
Neighborhood Watch	Save all buildings outside the missile silo from destruction.
40 Points
The One Free Bullet	Clear Episode One firing exactly one bullet. Grenade, crowbar, rocket, and Gravgun kills are okay.
Aperture Science	Gain gold medals on all Portal challenges.

5 Points
Gunishment!	Destroy the Combine cannon in the junkyard.
Secondary Silo Secured	Secure the launch doors on missile silo 2.
Twofer	Overcome both antlion guards outside the White Forest.
Submissive	Put the can in the trash in Half-Life 2.
Where Cubbage Fears to Tread	Defend Little Odessa from the gunship attack in Half-Life 2.
Hallowed Ground	Escort Gregori safely through the church cemetery in Half-Life 2.
Defiant Achievement	At the beginning of Half-Life 2 where the carbine cop asks you to pick up the can, pick it up and hit him with it.
10 Points
Quiet Mountain Getaway	Survive the ambush at White Forest Inn.
Meet the Hunters	Survive the Hunter ambush with Alyx.
20 Points
Defense of the Armament	Save the missile silo from the Combine offensive.
25 Points
Singularity Collapse	Destroy the Citadel's reactor core in Half-Life 2.

- 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 begin. 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.

- Hidden Left 4 Dead trailer
Remain idle at the game selection screen. After a few minutes, a demo video of one of the games will begin. After the video ends, wait for the next video to begin, which will be a Left 4 Dead trailer.

- Fire rocket projectile
While you are playing this game, press Up, Y(2), B(2), A(2), X(2), Up.

- Faster construction
As an engineer, do not wait for your building. Just whack it with the wrench so that it builds faster.

- Create box
While you are playing this game, press Down, B, A, B, Y, Down, B, A, B, Y. Notice: Enabling this code will prevent achievements from being earned.

- Improve Portalgun from Blue only to Blue and Orange
While you are playing this game, press X, B, LB, RB, Left, Right, LB, RB, LT, RT. Notice: Enabling this code will prevent achievements from being earned.

- Invincibility
While you are playing this game, press LB, Up, RB, Up, LB(2), Up, RB(2), Up.

- Portal placement anywhere
While you are playing this game, press Y, A, B, A, B, Y(2), A, Left, Right. Notice: Enabling this code will prevent achievements from being earned.

- Refill ammunition for current weapon
While you are playing this game, press Y, B, A, X, RB, Y, X, A, B, RB to spawn an ammunition cartridge for your current weapon.

- Restore health
While you are playing this game, press Up(2), Down(2), Left, Right, Left, Right, B, A to spawn a medpak that will restore 25 points of health.

- Portalgun ID 1
While you are playing this game, press Up, Left, Down, Right, Up, Left, Down, Right, X(2).

- Invincibility
While you are playing this game, press LB, Up, RB, Up, LB(2), Up, RB(2), Up.

- Getting past turrets and other dangerous enemies
When you need to run a long way and have some objects with you (for example, a non-explosive barrel), if you have the Gravity Gun, use it as cover, and run (while facing the enemy) to the other side. Then if possible, shoot the barrel at the enemy. Notice: Make sure there is only one enemy when doing this. Also, make sure the object is indestructible, and most importantly, look at the enemy and see if you can kill it with one shot.

Half-Life 2: Episode One

- ApertureScience.com hidden message
While logged into the ApertureScience.com website, type 'THECAKEISALIE' to access a hidden message left by some employees.

- No clipping mode
While you are playing this game, press Up(3), LB, Up(3), RB, Up(2).

- Kill
While you are playing this game, press LB, Down, RB, Down, LB(2), Down, RB(2), Down.

- Invincibility
While you are playing this game, press LB, Up, RB, Up, LB(2), Up, RB(2), Up.

- Enemies do not target you
While you are playing this game, press Down(3), LB, Down(3), RB, Down(2).

- Restore health
While you are playing this game, press Up(2), Down(2), Left, Right, Left, Right, B, A to spawn a medpak that will restore 25 points of health.

- Hidden pumpkins
Set the system date to October 31. After you are ambushed by Hunters and Combine at a big house, drive along the road. Near where the supply cache is found, you will see an old truck. Go up to it, and there will be lots of pumpkins lying on the ground.

- Lost reference
When you enter the White Forest base, you meet a Vortigaunt in a lab coat named Uriah. When you first enter the room where you meet Uriah, there is a gas tank against the back wall. Behind that tank is a small room with a computer that has a sequence of numbers on it. This is a reference to the TV show Lost that Gabe Newell added due to the fact that he and the creator of Lost were close friends.

Portal

- Restore health
While you are playing this game, press Up(2), Down(2), Left, Right, Left, Right, B, A to spawn a medpak that will restore 25 points of health.

- 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.

- Portalgun ID 0
While you are playing this game, press Up, Left, Down, Right, Up, Left, Down, Right, Y(2).

- Portalgun ID 2
While you are playing this game, press Up, Left, Down, Right, Up, Left, Down, Right, A(2).

- Portalgun ID 3
While you are playing this game, press Up, Left, Down, Right, Up, Left, Down, Right, B(2).

- Wireframe cycle
While you are playing this game, press LB(2), RB(2), LB, RB, LB, RB, Left, Right.

- Refill ammunition for current weapon
While you are playing this game, press Y, B, A, X, RB, Y, X, A, B, RB to spawn an ammunition cartridge for your current weapon.

- No clipping mode
While you are playing this game, press Up(3), LB, Up(3), RB, Up(2).

- Level select
While you are playing this game, press Left(4), LB, Right(4), RB to unlock all levels.

- Level select
While you are playing this game, press Left(4), LB, Right(4), RB to unlock all levels.

- Easy achievements
Play a game with just you and a friend. Have your friend let you repeatedly kill him or her to easily get achievements.

- Level select
While you are playing this game, press Left(4), LB, Right(4), RB to unlock all levels.

- Fire energy ball
While you are playing this game, press Up, Y(2), X(2), A(2), B(2), Up. Notice: Enabling this code will prevent achievements from being earned.

- No clipping mode
While you are playing this game, press Up(3), LB, Up(3), RB, Up(2).

- Enemies do not target you
While you are playing this game, press Down(3), LB, Down(3), RB, Down(2).

- Alternate title screen
Successfully complete the game to unlock the cake title screen.

- AA
While you are playing this game, press Y, Up, Y, Right, Y, Down, Y, Left, Y, Up.

- Level select
While you are playing this game, press Left(4), LB, Right(4), RB to unlock all levels.

- Refill ammunition for current weapon
While you are playing this game, press Y, B, A, X, RB, Y, X, A, B, RB to spawn an ammunition cartridge for your current weapon.

- Overheating Xbox 360
Play the level where you face off with the laser guided robots. Once you get past the first few robots, you must begin dropping the boxes on the robots heads so they fall over. In the little area where you find the first two boxes, crouch and walk behind where the boxes were. You will find a little room with odd music playing and graffiti on the walls that says things such as 'The cake is a liar'. There also seems to be an Xbox 360 with a pot inside of it. The Xbox 360 is overheating and boiling the water.

Team Fortress 2

- Alternate title screen
Successfully complete the game to alternate the title screen.

- Enemies do not target you
While you are playing this game, press Down(3), LB, Down(3), RB, Down(2).

Half-Life 2: Episode Two

- 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.