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.
Shut down AEGIS in Advanced Mode
Experience a Deeply Unimpactful Moment
Find all the Vitrified door messages
Get crushed in the door
Not even all the way!
Find the radio under the stairs
Refuse to Listen
Get shot on the turret range
MAKE IT STOP
Try to bring the cube with you
Check that all doors have been locked for the night
Get off the track again
Reach AEGIS's Domain
Get burned whilst in the goo
Get into the vents
Mind your Step
Solve the broken test
Enter Virgil's testing track
Solve the same test three times!
Hide from AEGIS
Get electrocuted
Ignore good advice
Enter the main lobby of Aperture Science Innovators
Oversleep
Who is that?
Discover a new way to turn down the heat
Super Drowning Skills
Shutdown AEGIS in Story Mode