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