Here is the full list of all 18 Blackwell Deception achievements. It takes around 8-10 hours to unlock all of the achievements on Windows.
Finish the game in commentary mode
Complete the game once
Come back from the void
Free Rosa
Not bad, for a dead guy
Find Jamie's favorite song
Use Joey's breath ability on at least 10 people
Use Rosa's business card for an unintended purpose
Find a lost item
Visit another psychic
Get out of a sticky situation
Sometimes you've gotta rob a few old ladies...
Abuse an innocent
Escape the yacht with only getting shot once
Open the secret compartment on the first try
Find all the references to previous games in Rosa's apartment
Save a ghost... and yourself
Use both Rosa and Joey to solve a puzzle