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