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