Here is the full list of all 21 Richard & Alice achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
You went off to uncharted territory.
But is it justice, or revenge?
You parted ways... amicably.
You made your final decision.
You finally understand each other.
You escaped from prison, and uncovered the truth.
You talked to Alice about your family... again.
You know what you did.
You found and read all the documents.
You gave Barney a keepsake.
You escaped from certain death, irresponsibly.
You desecrated a church, but don't feel too guilty.
You defied death and retrieved the mysterious box.
You called for help… but no-one came.
You took Barney to his dad's grave. Or did you?
You used cleaning supplies incorrectly and got very upset.
You moved into a nice new house. Sort of.
You gave Alice the guided tour.
You watched the highly accurate TV adaptation of Analogue: A Hate Story.
You used a child's toy to escape from the basement.
You encouraged Alice to begin opening up.