Here is the full list of all 63 Neon White achievements.
Defeat Green at the Clocktower before he reaches the top floor
Defeat Green at the Third Temple before he reaches the final stage
Complete Yellow's Hell Rush
Complete Yellow's Heaven Rush
Complete Violet's Hell Rush
Complete Violet's Heaven Rush
Complete Mikey's Heaven Rush
Complete Red's Heaven Rush
Complete Red's Hell Rush
Unlock one last memory
Write Green into the Book of Life
Complete 100% of the game
Unlock all of White's memories
Complete your relationship with Red
Complete Red's Sidequests
Complete your relationship with Raz
Complete your relationship with Violet
Complete Violet's Sidequests
Complete your relationship with Mikey
Collect all gifts
Earn an Ace medal on every level
Complete your relationship with Yellow
Complete Yellow's Sidequests
Complete your relationship with Green
Unlock one of Red's memories
Collect 50% of the total gifts
Unlock one of Violet's memories
Unlock one of Yellow's memories
Complete White's Heaven Rush
Deplete the Fists card
Use the Fists card
Discovered Idiot Island
Restore Heaven
Complete Mission 12
Write Green into the Book of Death
Defeat Green at the Hand of God
Earn 50% of the total Ace medals
Complete Mission 11
Use the Book of Life Card on a Mimic
Redeem every Heavenly Delight Ticket
Complete Mission 10
Defeat Green at the Third Temple
Find a Strange Coin
Complete Mission 9
Complete Mission 8
Stomp off of the edge of a level
Complete Mission 7
Die from a Mimic's bullet
Complete Mission 6
Get killed by a Tripwire
Complete Mission 5
Collect ten cards from vending machines
Complete Mission 4
Defeat Green at the Clocktower
Complete Mission 3
Kill an enemy by parrying a bullet at them using the Katana card
Complete Mission 2
Redeem a Heavenly Delight Ticket
Give your first gift
Earn your first Ace medal
Complete Mission 1
Complete White's Hell Rush
Complete Mikey's Hell Rush