Here is the full list of all 15 bit Dungeon II achievements. It takes around 2-3 hours to unlock all of the achievements on Windows.
Find an epic-quality weapon.
Free the ghost from her grave.
Slay the Demiurge.
Tis this a demon?
You have died. You have all lost things. You can not take your possessions with you to the next incarnation.
Enter into the Dark World.
Face The Eater!
Destroy the Soul Collector.
Kill the king of Skeletons.
She rules an army of beasts in the Black Church, defeat The Yaldabaoth.
Slayed the Fiend.
Slay the Fire Nob Glob.
Kill the leader of the Thief Kings, The Cursed Wizard!
Reach level ten.
Kill a mini-boss.