Full list of all 28 Portal Stories: Mel achievements. It takes around 6-8 hours to unlock all of the achievements in the base game on Windows.
The base game contains 27 achievements, and there is 1 DLC pack containing 1 achievements.
Refuse to Listen
Get crushed in the door
Find all the Vitrified door messages
Experience a Deeply Unimpactful Moment
Super Drowning Skills
Get electrocuted
Reach AEGIS's Domain
Get shot on the turret range
Get off the track again
Get burned whilst in the goo
Solve the broken test
Solve the same test three times!
Hide from AEGIS
Ignore good advice
Enter Virgil's testing track
Discover a new way to turn down the heat
Who is that?
Oversleep
Check that all doors have been locked for the night
Enter the main lobby of Aperture Science Innovators
Try to bring the cube with you
Shut down AEGIS in Advanced Mode
Find the radio under the stairs
Not even all the way!
Get into the vents
Mind your Step
MAKE IT STOP
Shutdown AEGIS in Story Mode