Here is the full list of all 16 Soul Survivor: Trials of the Goddess achievements.
You've purchased an Upgrade from the special vendor.
You've completed the main story on Normal Mode.
You've unlocked the alternate ending to the main story.
You have been defeated, but your Soul lives on! (lost a Life on Normal Mode)
You've defeated the Guardians of the Wasteland. (defeated any Chapter 1 end-boss)
You've defeated the Guardians of the Dungeon. (defeated any Chapter 2 end-boss)
You've completed the Legacy Campaign.
You've reached experience level 10.
You've discovered the secret Area in Chapter 1.
You've discovered the secret Area in Chapter 2.
You've discovered the secret Area in Chapter 3.
You've completed the main story on Normal mode without losing any Lives.
You've completed the main story on Normal mode in under 2 hours.
You've defeated the hidden boss in Chapter 1.
You've defeated the hidden boss in Chapter 2.
You've defeated the hidden boss in Chapter 3.