Here is the full list of all 8 The Chosen RPG achievements. It takes around 3-4 hours to unlock all of the achievements on Windows.
Myste has joined your party
Serenity has joined your party
Visit your mother's grave and find her bangle
Trinity has joined your party
You have defeated Akuma
Edge was able to speak with his Mother
You awoke the Dragon and defeated him
You defeated the most powerful monster in Rosefalcon