This is the Lazy Gamer video guide for all of the missable achievements in the single player campaign for Portal 2. If you need the co-op achievements, click here, and for full chapter walkthroughs, click here, or just use the links at the bottom of the page
Chapter 2: The Cold Boot
Drop
Box
This achievement is obtained in test chamber six of this chapter.
Final
Transmission
This achievement is obtained in test chamber six of this chapter.
Pturretdactyl
This achievement is obtained in test chamber six of this chapter.
Preservation of Mass
This achievement is obtained in test chamber seven of this chapter.
Chapter 3: The Return
Overclocker
This achievement is for beating test chamber 10 (the second test chamber in this chapter) in 70 seconds or less.
Chapter 4: The Surprise
Good
Listener
When you are making your escape, you'll hear GLaDOS mention the last test and you will not be able to miss the test chamber opening up to your left. Complete the test chamber to get the achievement.
Chapter 5: The Escape
No
Hard Feelings
When you reach the turret redemption line and you are on the second conveyor belt, you'll see the laser sight of a functioning turret coming towards you. Just pick the turret up to get this achievement.
Scanned
Alone
When you get to the part where you have to remove the turret from the template scanner, just step into the scanner to get this achievement.
Chapter 6: The Fall
Door
Prize
For this achievement, there are a total of six doors you have to find and push a button beside each door to listen to some really funny commentary from Cave Johnson. They are split up into two groups of three doors. The first group of doors is found after you get to the top of the lift right after you first hear Cave Johnson talking. The second group of doors is found in an office above the control room where you pick up potato GLaDOS.
Ship
Overboard
In the same area as the second group of doors for Door Prize, go outside on the catwalk and look at the life preserver to get this achievement.
Schroedinger's
Catch
This achievement is obtained in test chamber 1958 28. You'll see the cube in a glass box in the middle of the room. You have to catch the cube before it touches the ground, so just reload your checkpoint if you miss it.
Chapter 7: The Reunion
Portrait
of a Lady
This achievement is obtained right after exiting the very first test chamber in this chapter.
Chapter 8: The Itch
You
Made Your Point
During the first test after GLaDOS uses the paradox, just stand around for a minute after getting off the lift and you'll get the achievement.
Smash
TV
There are a total of eleven monitors you need to break during this chapter to get the achievement, starting with the monitor in test chamber one.
Chapter 9: The Part Where...
Pit
Boss
This achievement is obtained at the very beginning of the chapter.