Here is the full list of all 20 Illusoria achievements.
You died 10 times
You died 100 times
You toyed with the first nightmare
You discovered all the scrolls
You ignored Wolfgang
You found the missing head
You found the first brother
You found the second brother
You found the third brother
You found the fourth brother
You found the fifth brother
You found the sixth brother
Finished each level without dying
You destroyed Illusoria
You saved Illusoria
You injured one of the brothers before they could escape
You killed Monster Amelia without knocking her out once
You killed all fifty shades without dying
You found the lost doll
You managed to finish the game on one sitting