14.05%
Four Ring Circus
Enter 4 different portals without touching the ground in co-op
15.27%
Final Transmission
Find the hidden signal in one of the Rat Man's dens
15.69%
Schrodinger's Catch
Catch a blue-painted box before it touches the ground
15.90%
Door Prize
Examine all the vitrified test chamber doors
16.57%
Narbacular Drop
Place a portal under your co-op partner while they are gesturing
17.36%
You Made Your Point
Refuse to solve the first test in Chapter 8
17.59%
Pit Boss
Show that pit who's boss
19.27%
Pturretdactyl
Use an Aerial Faith Plate to launch a turret
19.43%
Asking for Trouble
Taunt GLaDOS in front of a camera in each of the five co-op courses
21.05%
Ship Overboard
Discover the missing experiment
22.08%
Rock Portal Scissors
Win 3 co-op games of rock-paper-scissors in a row
22.37%
Can't Touch This
Dance in front of a turret blocked by a hard light bridge in co-op