Here is the full list of all 15 One More Dungeon achievements.
Finish the level in under 2 minutes
Сomplete the game with "No margin for error" or "Curse" mutator
Put the items in all the inventory slots
Сomplete the game with "Fog" or "Broken cartridge" mutator
Buy all the mutators
Spend 50 coins
Сomplete the game
Сomplete eight levels
Squash 25 bugs
Die after drinking the poison
Kill the Ancient Necromancer
Сomplete five levels
Kill the Elder Flower
Start the game with any mutator
Сomplete the first level