Here is the full list of all 8 The Blackwell Legacy achievements. It takes around 4-5 hours to unlock all of the achievements on Windows.
Finish the game with both commentary modes active, from the opening menu till the end
Finish the game at least once
Save the Deacon's soul
Convince the Deacon to move on without resorting to violence
Bluff your way past the guard on your first attempt
Rosa, meet your new life partner
Get Joey to tell you everything he knows about your family
Never talk to Joey in public