Here is the full list of all 18 Blackwell Epiphany achievements.
Finish the game in commentary mode (from the first screen till the last)
Complete the story
Try to lie your way out of it
Create no more than 450 footprints
Somebody's got to do it...
Free yourself
Learn a long kept secret
Blow on everyone you can find
The hows and whys of Joey
Reunite a family
Two becomes one
Make a leap without falling once
Find a secret room
Keep clam and keep cool
She has plenty of time...
Gain access to an online game
Save your first ghost
Solve a puzzle together