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