Here is the full list of all 48 The Messenger achievements. It takes around 15-20 hours to unlock all of the achievements on Windows.
Defeat the Necromancer
Buy five upgrades in the shop
Destroy a Big Time Shard
Meet Quarble
Destroy your first Power Seal
Attack your first enemy projectile
Be lectured on happiness
Beat the intro without dying
Rescue all Phobekins
Jump down the big waterfall in Bamboo Creek
Defeat the Emerald Golem
Defeat the Queen of Quills
Defeat Colos & Suses
Get to the top of the mountain
Defeat the Arcane Golem
Time travel to the future
Defeat the Sky Serpent
Defeat the Demon General
Ride Manfred around the world back to where it all started
Make it out of the underwater labyrinth
Bump on a few flowers in Rivière Turquoise
Run on lava
Defeat the Demon King
Complete the Elemental Skylands scenario
Survive the Corrupted Future chase
Receive the Key of Love
Complete the Melody
Defeat Phantom
Beat the game
Execute 15 Cloudsteps without landing or clinging to a wall
Make it through Dark Cave without the 'Power of True Sight'
Destroy all Power Seals
Buy all upgrades from the shop
Enter all areas of the world
Be lectured on the power of stories
Be lectured on the inner child
Buy the Swim Dash upgrade from the shop
Kill a green demon in a single hit
Keep a windmill shuriken going for 15 seconds
Make it from the beginning of the game to beating the Queen of Quills with zero deaths
Defeat Octo
Defeat the Voodoo Totem
Defeat the Demon General... again
Win the race with a perfect score
Make your first purchase at the Craftman's Corner
Meet the voodoo mask
Unclog the Money Sink
Accept 'THE DEAL'