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.
Slayed the Fiend.
Slay the Fire Nob Glob.
Free the ghost from her grave.
Find an epic-quality weapon.
Slay the Demiurge.
Tis this a demon?
Enter into the Dark World.
She rules an army of beasts in the Black Church, defeat The Yaldabaoth.
Kill the king of Skeletons.
Face The Eater!
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!
Reach level ten.
Destroy the Soul Collector.
Kill a mini-boss.