Here is the full list of all 18 Longest Monday: Unveiling achievements.
Set the calendar to Tuesday 5 times
Get fired
Reveal the secret of the woman in a hat
Reveal the secret of the janitor
Team up with the blonde woman to get your boss arrested
Side with your boss
Get your boss arrested at the cost of admin's life
Witness the robots' departure
Refuse to bring the janitor water
Get a cactus flower
Talk with everyone on your first Monday at work
Learn the name of the woman in a hat
Roll over on the admin
Complete chapter 1
Complete chapter 2
Complete chapter 3
Complete chapter 4
Complete chapter 5