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