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