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