Here is the full list of all 38 Moss achievements.
Rescue Argus without a single death.
Destroy two or more Screecher enemies with a controlled Ticker.
Find a low-hanging path to the town pub.
Use your power as a Reader to break many objects.
Collect all of the Relic Dust.
Break everything within the town pub that can be broken.
Collect all of the forgotten fragments.
Destroy a Forged enemy with a controlled Scorcher.
Destroy a Forged enemy with an aerial attack.
Use Quill's sword to cut down a lot of grass.
Finish the first book of Moss.
Startle Quill from behind.
Defeat the serpent Sarffog.
Climb to the castle bridge alongside Quill.
Annoy Quill by delaying the adventure.
Collect a large amount of Relic Dust.
Guide Quill to destroy multiple thorn patches.
Enter the Abandoned City alongside Quill.
Enter the Namelhook Mining cave alongside Quill.
Take control over many Forged enemies.
Unlock the path to the Mire Temple's altar room.
Light the torches of the Knights of the Sun.
Give Quill a high five.
Collect a small amount of Relic Dust.
Use a Screecher to unlock the path forward.
Enter the Mire Temple alongside Quill.
Defeat the Screechers first encountered in the Mire.
Use your power as a Reader to heal Quill for the first time.
Follow the Starthing and Quill into the impassable Mire.
Enter the Clearing alongside Quill.
Discover your first Forgotten Piece.