Here is the full list of all 20 Master Reboot achievements. It takes around 6-8 hours to unlock all of the achievements on Windows.
Complete the Final Level in record time
Complete the full game in Welsh
Find the alternative ending
Find all the virus symbols
Hit all the viruses in the Graveyard Level
Find all of the blue ducks
Touch the whale on the Beach Zero Level
Complete the Hospital Level without a torch
Complete the Aeroplane Level without dying
Complete the Street Level without taking a hit
Complete the planet puzzle in the School Level without checking the answer
Complete the full game
Get the monorail to the Mainframe
Make the right choice in the Library
Get crushed by a bookcase in the Library
Find half of the blue ducks
Go down the wrong path in the Fairground Zero Level
Listen to the radio show in your Soul Village
Attacked by the virus in the closet
Read the employee handbook