Here is the full list of all 86 Ato achievements.
Collect all runes
Collect EVERYTHING
Defeated Berserker
Obtain all scrolls
Defeated Turtle
Completed Armor Arena
Max out your magic meter
Defeated Vagrant
Obtain all talismans
Beat Ato on Accessible Difficulty
Beat Ato on Experienced Difficulty
Defeated Leader
Defeated Demon
Completed Fatal Arena
Defeated Champ
Defeated Blameless
Collect all coins
Defeated Archer
Defeated Tempest
Defeated Warden
Collect a magic bar
Defeated Tiny Warrior
Defeated Bandit
Completed Throw Arena
Defeated Cross Blade
Defeated Phantom Shin
Once obtained, Successfuly perform the counter ability on an enemy
Defeated Monk
Defeated Deceiver
Defeated Father Statue
Defeated Samurai
Completed Spin Arena
Defeated Daggerman
Defeated Sentinel
Defeated Geisha
Warp from one gate to another
Defeated Yari
Defeated Child Statue
Defeated Shadow Jin
Equip a Rune
Obtain your first Rune
Defeated Twins
Defeated Ancient Warrior
Defeated Mother Statue
Jump 1000 Times
Destroy a blue crystal block
Defeated Acolyte
Defeated Ninja
Obtain your first Coin
Defeated Guardian
Defeated Jin
Hit opponent 5 times while they are launched
Parry your opponent
Increase your max health
Obtain your first Talisman
Defeated Rogue
Defeat The Leader without killing his servants
Defeated Warden without the vision upgrade
Perform the just-frame legendary move
Perform the legendary move on an enemy
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