Here is the full list of all 29 INMOST achievements.
Defeat the first hunter.
Save the cat from the hunter
Finish the Old Man Scene
Find a hidden Pain Crystal
Finish the Girl Scene
Listen to the Storyteller's first tale.
Find the rabbit.
Get the Cookies.
Host a Tea Party!
Enter the mines.
Kill all jumpers.
Discover the fountain.
Discover what's in the attic.
Listen to all the rabbit's comments.
Find all the notes.
Listen to all the Storyteller's tales.
Talk to the cats when their sibling is dead.
Talk to the cats when their sibling is alive.
Collect all the Pain Crystals.
Finish the final scene.
Complete the castle scene without taking damage.
Complete the fire scene without taking damage.
Complete the swamp scene without taking damage.
Complete the Slime Pit scene without taking damage.
Complete the Snow scene without taking damage.
Kill all enemies as the Knight.
Zero deaths as the wanderer.
Play without collecting any pain.
Gain all the achievements.