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