Here is the full list of all 14 Shadows achievements.
Enter the Deep Below.
Enter the Ancient Hall.
Collect 50 Fireflies.
Solve the Runic Puzzle on your first try.
Collect 100 Fireflies.
Complete the game without dying.
Die and return to the start location 5 times.
Find all of the memories.
Reach 0 fireflies.
Enter the Skyward Pillars.
Enter the Luminous Caverns.
Enter the Stygian Maze.
Explore every room of the caves.
Find a secret room.