Here is the full list of all 27 The Slater achievements.
Kill a rat
Complete level 5 as Master
Complete level 5
Complete level 4
Complete level 4 as Master
Enter a secret observation room
Complete level 3
Shut down a metal detector
Complete level 2
Sabotage all security cameras in a level
Complete level 1
Kill a junkie
Complete the game
Poison a drink
Dress as lab worker
Trigger a car alarm
Chat with street bum
Start a lawn mower
Shoot a rat
Trigger police station upstairs alarm
Get party invitation without a kill
Sabotage ventilation system
Shoot a bird
Complete level 1 as Master
Complete level 2 as Master
Complete level 3 as Master
Complete level 6 as Master