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 at least once
Finish the game with both commentary modes active, from the opening menu till the end
Convince the Deacon to move on without resorting to violence
Get Joey to tell you everything he knows about your family
Never talk to Joey in public
Bluff your way past the guard on your first attempt
Save the Deacon's soul
Rosa, meet your new life partner