Here is the full list of all 13 Outbreak: The Nightmare Chronicles achievements.
Consumed a healing item.
They finally killed you.
Defeated a threat.
Solved your first puzzle.
Survived a campaign chapter or the Battle Mode.
Defeated twenty threats.
Defeated fifty threats.
Defeated 100 threats.
They finally... killed you again.
You died for a third time.
You died for a fourth time.
Solved ten puzzles.
Consumed ten healing items.