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