What is a trainer? A trainer is a program written to intercept and alter the memory addresses of games that are running in the background. Usually trainers contain such features as GOD MODE, UNLIMITED LIVES and others. Since trainers address specific memory locations, they are usually written to only support a specific version of a game.

Description: To find four turrets singing a song, find the turret inside a ventilation grate just past the elevator in Test Chamber 16. Jump over it, get the Refraction Cube, then use the laser to destroy that turret to open the grate. Enter the new area to find the four turrets singing a song.

Description: Play Chapter 2 "Test Chamber 6". Get the radio that appears in a clump of garbage into a window above the chamber after you hit a button. Work your way back through the level and place a portal on the pad across from the window. Use the launchers to get through the portal and into the room past the window, with radio in hand. Take the radio up to the wall to earn the Achievement / Trophy.

Description: Play Chapter 9. After Wheatley's surprise, portal away from the platform just as Wheatley sends arms to crush you. Do not run away on the catwalk. Stay nearby and Wheatly will beg you to come back. Stand at the edge of the pit overlooking his trap. He will ask you to just jump in the pit. Jump in to earn the Achievement / Trophy.

Description: Play Chapter 2 "Test Chamber 7". Keep track of the Companion Cube in this chamber. You can return to get it at the end of the level after using it to depress the button. Ignore GLadOS's comments and carry the cube through the broken "Emancipation Grill" at the end of the chamber to earn the Achievement / Trophy.

Description: Play Chapter 6 "The Fall" and reach the 1958 "28" room. There is a cube is trapped in a glass box and Blue Gel streaming out of a pipe in one corner in this room. Save the game. Shoot a portal under the Gel and over the crate to coat the cube. The cube will bounce until it breaks the glass. It will eventually break out of the glass. Catch this cube before it touches the ground to earn the Achievement / Trophy. *** Try standing between the entrance and the gel spout.

Description: Play Chapter 6 "The Fall" and reach the 1971-era test facility. Cave will begin talking about testing on hobos. Below one of the test spheres and a giant Aperture logo is a room marked "CONTROL ROOM" in yellow letters. Use a portal to get high above the Control Room and enter the small office. There is a cabinet with a door behind it in the corner of this office. Enter that door and follow the hidden hallway to a dock. At the end of the walkway near the docks is a orange life preserver marked "BOREALIS". Examine it to earn the Achievement / Trophy.

*** [Easter Egg] This is a reference to the Aperture ship "Borealis" that is seen at the end of Half Life 2: Episode 2.

Description: To unlock the specified Achievement, complete the following tasks. To view your achievements and stats in Steam, select "Community", then "My profile", then "View all my games", then the game and view stats.

Air Show

Perform 2 aerial gestures before touching the ground in co-op

Asking for Trouble

Taunt GLaDOS in front of a camera in each of the five co-op courses

Bridge Building

Complete all test chambers in the Hard-Light Surfaces co-op course

Bridge Over Troubling Water

Complete the first Hard Light Bridge test

Can't Touch This

Dance in front of a turret blocked by a hard light bridge in co-op

Confidence Building

Complete all test chambers in the Mass and Velocity co-op course

Door Prize

Examine all the vitrified test chamber doors

Drop Box

Place a cube on a button without touching the cube

Dual Pit Experiment

Do the same test twice

Empty Gesture

Drop your co-op partner in goo while they are gesturing by removing the bridge under them

Final Transmission

Find the hidden signal in one of the Rat Man's dens

Four Ring Circus

Enter 4 different portals without touching the ground in co-op

Friends List with Benefits

While playing co-op, hug 3 different people on your friends list

Gesticul-8

Perform all 8 gestures of your own volition in co-op

Good listener

Take GLaDOS' escape advice

High Five

Celebrate your cooperative calibration success

Iron Grip

Never lose a cube in Chamber 6 of the Mass and Velocity co-op course

Lunacy

That just happened

Narbacular Drop

Place a portal under your co-op partner while they are gesturing

No Hard Feelings

Save a turret from redemption

Obstacle Building

Complete all test chambers in the Excursion Funnels co-op course

Overclocker

Complete Test Chamber 10 in 70 seconds

Party of Three

Find the hidden companion cube in co-op test chamber

Pit Boss

Show that pit who's boss

Portal Conservation Society

Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements

Portrait of a Lady

Find a hidden portrait

Preservation of Mass

Break the rules in Test Chamber 07

Professor Portal

After completing co-op, complete Calibration Course online with a friend who hasn't played before

Pturretdactyl

Use an Aerial Faith Plate to launch a turret

Rock Portal Scissors

Win 3 co-op games of rock-paper-scissors in a row

SaBOTour

Make a break for it

Scanned Alone

Stand in a defective turret detector

Schrodinger's Catch

Catch a blue-painted box before it touches the ground

Ship Overboard

Discover the missing experiment

Smash TV

Break 11 test chamber monitors

Stalemate Associate

Press the button!

Still Alive

Complete Course 4 with neither you nor your co-op partner dying

Stranger Than Friction

Master the Propulsion Gel

Tater Tote

Carry science forward

Team Building

Complete all test chambers in the Team Building co-op course

The Part Where He Kills You

This is that part

Triple Crown

Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each