Here is the full list of all 11 bit Dungeon III achievements.
All Archons have been defeated.
Kill 100 Fiends
High equipment rarity total has been reached.
Free Sophia's Soul.
Assisted all neutral monsters.
Gain 50 souls from defeating bosses.
Kill 50 players and take their souls.
Equip all rune slots with rarity 3 and above.
Hunt down 25 elite monsters.
Defeat the Monad in the Darkworld
Unlock the Shade race.