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.
You have defeated Akuma
You awoke the Dragon and defeated him
Edge was able to speak with his Mother
You defeated the most powerful monster in Rosefalcon
Trinity has joined your party
Myste has joined your party
Serenity has joined your party
Visit your mother's grave and find her bangle