Here is the full list of all 86 Ato achievements.
Beat Ato on Accessible Difficulty
Beat Ato on Experienced Difficulty
Defeated Demon
Defeated Leader
Defeated Samurai
Defeated Geisha
Defeated Archer
Defeated Monk
Completed Throw Arena
Defeated Cross Blade
Defeated Phantom Shin
Defeated Warden
Completed Armor Arena
Defeated Turtle
Completed Spin Arena
Defeated Daggerman
Defeated Father Statue
Defeated Deceiver
Cut 50 stalks of bamboo
Equip a Rune
Obtain your first Rune
Defeated Twins
Defeated Ancient Warrior
Defeated Mother Statue
Defeated Yari
Hit opponent 5 times while they are launched
Defeated Child Statue
Jump 1000 Times
Warp from one gate to another
Destroy a blue crystal block
Defeated Acolyte
Parry your opponent
Defeated Ninja
Obtain your first Coin
Defeated Guardian
Increase your max health
Defeated Jin
Obtain your first Talisman
Defeated Rogue
Defeated Bandit
Defeated Berserker
Defeated Sentinel
Defeated Shadow Jin
Defeated Vagrant
Defeated Blameless
Defeated Champ
Defeated Tiny Warrior
Defeated Tempest
Completed Fatal Arena
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
Perform the legendary move on an enemy
Collect a magic bar
Obtain all talismans
Max out your magic meter
Obtain all scrolls
Collect all coins
Collect all runes
Collect EVERYTHING
Destroy 50 wall crystals
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