On Chapter 6 "The Fall", reach the 1958 "28" room. There is a cube that's trapped in a glass box and Blue Gel streaming out of a pipe in one corner in this room. Save the game, then shoot a portal under the Gel and over the crate to coat the cube. The cube will bounce until it breaks the glass and eventually break out of the glass. Catch this cube before it touches the ground and the achievement is yours.. Note: Stand between the entrance and the gel spout.
In Chapter 3, as you enter Test Chamber 17, look at the black wall high up to the left. Find the retracted plate and portal the lightbridge to get over to it. Behind the retracted plate is a mysterious, secret room filled with cups, art, and a poem on the wall.
The 11 monitors in Chapter 8 are those that broadcast Wheatley in the 10 puzzles (two monitors can be found in one puzzle). The monitors can be destroyed with falling blocks, lasers, and one must be taken out by catapulting bodily into it.
During your escape with Wheatly you will come across the 'Bring your daughter to work day' room, which contains all sorts of different science fair Potato projects. Go down to the very end of the line to find the over grown potato. Look closely to see that the owner of the project has written her name on one of the bottom corners; Chell.
Unlock the following Avatar Awards by performing the corresponding tasks:
AWARD - HOW TO UNLOCK Companion Cube - Complete Portal 2 Single Player. Love Shirt - Hug 3 friends in Portal 2 Coop. Portal 2 Hat - Survive the manual override. Portal 2 Shirt - Complete Portal 2 Coop Turret Shirt - Complete Test Chamber 10 in under 70 seconds.
On 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. Make your way back through the level and place a portal on the pad across from the window, then 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 and the achievement is yours.
On Chapter 2 "Test Chamber 7", keep track of the Companion Cube in this chamber. You may return to get it after using it to depress the button at the end of the level. Ignore GLadOS's comments and carry the cube through the broken "Emancipation Grill" at the end of the chamber and the achievement is yours.
To unlock this achievement, head to Chapter 8 and enter the first "real" test chamber that you have to do twice (after the room with the malfunctioning robots). Walk into the room until Wheatley starts talking and simply wait after a minute or so.
As your continue through Wheatley's tests in Chapter 2, on test 15, zoom into the area where he is "making" an exit for you. Near the door you can see Peabody getting startled and running through the exit door.
ACHIEVEMENTS - HOW TO UNLOCK Pit Boss (30 points) - Show that pit who's boss. Preservation of Mass (20 points) - Break the rules in Test Chamber 07. Pturretdactyl (5 points) - Use an Aerial Faith Plate to launch a turret. Lunacy (20 points) - That just happened. Drop Box (20 points) - Place a cube on a button without touching the cube. Overclocker (30 points) - Complete Test Chamber 10 in 70 seconds. No Hard Feelings (10 points) - Save a turret from redemption. Schrodinger's Catch (20 points) - Catch a blue-painted box before it touches the ground. Ship Overboard (10 points) - Discover the missing experiment. Final Transmission (20 points) - Find the hidden signal in one of the Rat Man's dens. Good Listener (5 points) - Take GLaDOS' escape advice. Scanned Alone (5 points) - Stand in a defective turret detector. The Part Where He Kills You (20 points) - This is that part. Bridge Over Troubling Water (10 points) - Complete the first Hard Light Bridge test. SaBOTour (10 points) - Make a break for it. Stalemate Associate (15 points) - Press the button!. Wake Up Call (5 points) - Survive the manual override. You Monster (5 points) - Reunite with GLaDOS. Undiscouraged (10 points) - Complete the first Thermal Discouragement Beam test. White Out (15 points) - Complete the first Conversion Gel test. Tunnel of Funnel (15 points) - Master the Excursion Funnel. Dual Pit Experiment (15 points) - Do the same test twice. Tater Tote (15 points) - Carry science forward. Vertically Unchallenged (15 points) - Master the Repulsion Gel. Stranger Than Friction (15 points) - Master the Propulsion Gel. Professor Portal (75 points) - After completing co-op, complete Calibration Course online with a friend who hasn't played before. Air Show (20 points) - Perform 2 aerial gestures before touching the ground in co-op. Portal Conservation Society (20 points) - Complete Chamber 3 in the Hard-Light Surfaces co-op course using only 5 total portal placements. Empty Gesture (25 points) - Drop your co-op partner in goo while they are gesturing by removing the bridge under them. Party of Three (25 points) - Find the hidden companion cube in co-op test chamber. Narbacular Drop (25 points) - Place a portal under your co-op partner while they are gesturing. Asking for Trouble (10 points) - Taunt GLaDOS in front of a camera in each of the five co-op courses. Rock Portal Scissors (20 points) - Win 3 co-op games of rock-paper-scissors in a row. Friends List With Benefits (50 points) - While playing co-op, hug 3 different people on your friends list. Four Ring Circus (25 points) - Enter 4 different portals without touching the ground in co-op. Triple Crown (15 points) - Solve 3 co-op chambers in the Mass and Velocity course in under 60 seconds each. Still Alive (15 points) - Complete Course 4 with neither you nor your co-op partner dying. Can't Touch This (10 points) - Dance in front of a turret blocked by a hard light bridge in co-op. Smash TV (75 points) - Break 11 test chamber monitors. High Five (5 points) - Celebrate your cooperative calibration success. Team Building (10 points) - Complete all test chambers in the Team Building co-op course. Door Prize (20 points) - Examine all the vitrified test chamber doors. Portrait of a Lady (10 points) - Find a hidden portrait. You Made Your Point (10 points) - Refuse to solve the first test in Chapter 8. You Saved Science (100 points) - Complete all test chambers in all courses of co-op. Iron Grip (20 points) - Never lose a cube in Chamber 6 of the Mass and Velocity co-op course. Gesticul-8 (15 points) - Perform all 8 gestures of your own volition in co-op. Confidence Building (10 points) - Complete all test chambers in the Mass and Velocity co-op course. Bridge Building (15 points) - Complete all test chambers in the Hard-Light Surfaces co-op course. Obstacle Building (15 points) - Complete all test chambers in the Excursion Funnels co-op course.
This achievement is unlocked at the start of Chapter 7: The Reunion. On the catwalks between tests 1971-01 and 1971-02, while facing the entrance to the 02 room, place a portal on the wall to your right and look for another pad you can shoot a portal onto through the gate and past the stairs to the left. On the other side of the portal is an office with a big portrait of Cave Johnson and what seems to be Caroline. Stare at the portrait and GLadOS will comment on it, giving you the achievement.
Find the turret inside a ventilation grate just past the elevator in Test Chamber 16 and jump over it to get the Refraction Cube. Then, use the laser to destroy that turret to open the grate. Enter to find four turrets singing a song.
When going for the "Ship Overboard" achievement, there are three metal doors in the hallway once you enter the door behind the filing cabinet . If you activate the doors, Cave Johnson talks about the tests. Activate all three doors and the achievement is yours.
In the first test chamber, after discovering white gel (where it comes down from a pipe infinitely), stay in the chamber for a really long time (about 10 minutes or so) and Cave Johnson will reveal secrets about Caroline and GLaDOS in a long monologue.
Well here we are again, It’s always such a pleasure, Remember when you tried to kill me twice? Oh, how we laughed and laughed, Except I wasn’t laughing, Under the circumstances I’ve been shockingly nice.
You want your freedom take it, That’s what I’m counting on, I used to want you dead but, Now I only want you gone.
She was a lot like you, (Maybe not quite as heavy), Now little Caroline is in here too. One day they woke me up, So I could live forever, It’s such a shame the same will never happen to you.
You’ve got your short, sad life left, That’s what I’m counting on, I’ll let you get right to it, Now I only want you gone.
Goodbye, my only friend, Oh, did you think I meant you? That would be funny if it weren’t so sad, Well you have been replaced, I don’t need anyone now, When I delete you maybe I’ll stop feeling so bad.
Go make some new disaster, That’s what I’m counting on, You’re someone else’s problem, Now I only want you gone, Now I only want you gone, Now I only want you gone.
To get the co-op action "Hugs," go to the last level of the Hard Light Chamber (just before you insert the disk) where you must launch each other in the air and make each other collide. If successful, the robots will hug.
On Chapter 9, after Wheatley's surprise, portal away from the platform just as Wheatley sends arms to crush you. Instead of running, stay nearby and Wheatly will beg you to come back. Stand at the edge of the pit overlooking his trap until he asks you to just jump in the pit. Jump in and the achievement is yours.
In Chapter 4, when escaping from GLaDOS with Wheatley, GLaDOS will attempt tricking you with "one last test." Make a save (so you don't have to backtrack) and head towards the heart she makes on the wall and the door leading to what appears to be a forest. Once you cross the lightbridge, you'll unlock the Good Listener achievement.
On Chapter 5 "The Escape", reach the conveyor belts carrying droids to the incinerator. Use a portal to get onto the conveyor belt and walk on the belt until a droid with a working laser beam appears. Pick it up and the achievement is yours.
On Chapter 6 "The Fall", reach the 1971-era test facility and 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" with yellow letters. Use a portal to get high above the Control Room. Enter the small office. Enter the door behind the cabinet 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 and the achievement is yours.. Note: This is a reference to the Aperture ship "Borealis" that is seen at the end of Half Life 2: Episode 2.