The The Only Traitor Add-on for The Final Station has 13 achievements.
Finish the game with Thomas
Shoot a horse.
Learn all the story of Harry
Finish the game with Jesse
Finish the game with Bill
Finish the game with Brandon
Finish the game with Matthew
Finish the game with Bob
Finish the game with Charles
Finish the game with Marc
Finish the game with an "old friend"
Finish the game with a soldier
Finish the game without any passengers