Here is the full list of all 52 Lone Fungus achievements.
Learn everything you can from the Grand Librarian
Parry 200 Projectiles
Listen what the Professor Statue has to say about each mushroom cap
Achieve 100% completion and finish the game (True Ending)
Collect all Astral Fragments
Collect 75 Mindshrooms
Collect all Relics
Fully upgrade your sword's damage
Collect all Ladybugs
Read all the 'Ten Commandments' tablets
Open all levered one way gates
Unlock the Royal Ornament
Unlock the Teleportation Wand
Leave the Kingdom (Abandonment Ending)
Downward Slash the Bouncy Spore 5 times in a row without touching the ground
Unlock all Bounce abilities
Collect all Emblems
Talk to every Major Statue
Collect all Spell Stones
Collect all Health Crystals
Complete the game (True Ending / Selfish Ending)
Fullfill your destiny on the 'Normal' Difficulty (True Ending)
Collect 50 Mindshrooms
Learn both Great Slashes
Acquire the Spark Ball Spell
Collect all Brain Nodes
Acquire the Vibrant Crystal Spell
Acquire the Berserk Spell
Acquire the Golden Light Spell
Cut 1000 Flowers/Flora
Unlock the Fire Bounce ability
Acquire the Spicy Nut Spell
Acquire the Returning Contraption Spell
Unlock the Crouch Jump ability
Defeat 500 Enemies
Collect 25 Mindshrooms
Unlock the Spin Jump
Unlock the Wall-Bounce ability
Acquire the Acid Hammer Spell
Collect 4 Health Crystals
Acquire the Boost Projectile Spell
Acquire the Bouncy Ball Spell
Acquire the Bouncy Spore Spell
Unlock both the Dashes
Defeat 100 Enemies
Learn how to Conjure a Mushmover
Unlock the Mushmover Infusion ability
Use the Bouncy Spore Spell to reach somewhere higher up
Fullfill your destiny on the 'Hardcore' Difficulty (True Ending)
Fullfill your destiny on the 'Nightmare' Difficulty (True Ending)
Forget the past, reincarnate only the Greencap culture of mushrooms (Selfish Ending)
Achieve 100% completion and finish the game on the 'Nightmare' Difficulty (True Ending)