Here is the full list of all 86 Ato achievements.
Beat Ato on Accessible Difficulty
Beat Ato on Experienced Difficulty
Defeated Demon
Obtain all scrolls
Completed Fatal Arena
Defeated Champ
Defeated Blameless
Defeated Leader
Defeated Tempest
Obtain all talismans
Defeated Archer
Collect all coins
Defeated Monk
Perform the legendary move on an enemy
Completed Armor Arena
Defeated Turtle
Defeated Deceiver
Defeated Father Statue
Defeated Samurai
Completed Spin Arena
Defeated Daggerman
Defeated Warden
Defeated Geisha
Defeated Shadow Jin
Completed Throw Arena
Defeated Cross Blade
Defeated Phantom Shin
Defeated Yari
Hit opponent 5 times while they are launched
Defeated Child Statue
Defeated Sentinel
Warp from one gate to another
Defeated Bandit
Defeated Ancient Warrior
Defeated Mother Statue
Equip a Rune
Obtain your first Rune
Defeated Twins
Jump 1000 Times
Destroy a blue crystal block
Defeated Acolyte
Parry your opponent
Defeated Ninja
Obtain your first Coin
Increase your max health
Obtain your first Talisman
Defeated Rogue
Defeated Jin
Defeated Guardian
Defeated Berserker
Defeated Vagrant
Defeated Tiny Warrior
Defeat The Leader without killing his servants
Defeated Warden without the vision upgrade
Once obtained, Successfuly perform the counter ability on an enemy
Perform the just-frame legendary move
Collect a magic bar
Max out your magic meter
Collect all runes
Collect EVERYTHING
Destroy 50 wall crystals
Cut 50 stalks of bamboo
Beat Ato on Bushido Difficulty
Beat the first 3 bosses on Hell Difficulty
Beat Ato on One Hit Difficulty Mode
Beat Ato without collecting a Rune
Beat Ato without obtaining a dodge ability
Beat Ato without collecting Talismans, Coins, Runes nor extra Magic
Beat Ato in 2 Hours