This is the Lazy Gamer video guide for all of the missable achievements in the co-op campaign for Portal 2. If you need the single player achievements, click here, and for full chapter walkthroughs, click here, or just use the links at the bottom of the page.
Narbacular
Drop
This achievement can be obtained in the hub area without even entering a testing course.
Co-op Course 1: Team Building
Four
Ring Circus
This achievement is best obtained in test chamber one of this course.
Co-op Course 2: Mass and Velocity
Iron
Grip
This achievement is obtained in test chamber six of this course.
Triple
Crown
This achievement is best obtained in test chambers two through four of this course.
Co-op Course 3: Hard-Light Surfaces
Portal
Conservation Society
This achievement is obtained in test chamber three of this course.
Empty Gesture
This achievement is also best obtained in test chamber three of this course.
Co-op Course 4: Excursion Funnels
Still Alive
To obtain this achievement, you must make it through the entire course without you or your partner dying. There are nine test chambers in the course.
Air
Show
This achievement is best obtained in test chamber one of this course.
Party
of Three and Can't Touch This
This achievement is obtained in test chamber nine of this course.